Bugs

On this page I've collected all bugs I'm aware of. Note that this also contains things that I consider broken (unbalancing), or suspect to be unintended, that might not strictly speaking be bugs. When possible, a solution or work around is mentioned too.
It's mostly meant for people to check if they experience something weird, to check if it is something wrong with the game or with what they do; not to demonstrate it's a worthless game, which it isn't. Just a prematurely released one. But I think with both the official and the unofficial patch the game is well playable, and for the unsolved bugs, there are a number of sites and people around to help you out.

Be aware that these bugs are described without trying to prevent spoiling, so if you haven't finished the game yet, you might not want to read here. Perhaps once I'll try to write a non-spoily warning list that starting players can use to prevent running into nasty bugs. But this is not it.

Several solutions to bugs consist of deleting MiniSaves; these are files in which the game stores the current state of area's you have visited, like the conversations you've had with NPCs, the last time the area spawned monsters, etc. But not if e.g. your party has solved quests there: that is stored in your savefile.
Deleting those files resets the area to as if you've never been there, which can solve crashes, fix problems with NPCs turned hostile, etc.
The MiniSaves are located in the folder with the same name, directly below the Might and Magic IX root directory; C:\Program Files\3DO\MM9 by default if I'm not mistaken. In this folder there are files for every location you have been to, and the names are readily recognizable. So if you need to reset e.g. Sturmford city, just delete all files that start with 'sturmfordcity'.

Some abbreviations I use below:
NPC = Non Player Character: all other (peaceful) humanoids in the game.
hNPC = hirable NPC, a NPC that can join you.

The bugs are ordered in these categories:

General

Crashes
With PCs there are so many hardware configurations that there will always be some that don't work well with any game. Apart from specific bugs described below, I haven't had very many problems with crashes, although the game occasionally just throws me back to Windows.
If you have crashes often, you might try to update your drivers, and directX. Klaravoyia's site (see the links page) has a number of useful driver links.
Crashes when entering town XXX
Some people have reported that their game always crashes when entering a specific city. Deleting the minisaves of that town has worked. (See here for details.)
Finding NPCs
Some NPCs, like trainers in Lindisfarne, or boatmen, sometimes take an underwater sight seeing tour; making it hard to find them.
Gatemaster hNPC
hNPC Ehwaz, gatemaster casts town portal on expert (only to nearest town), while promising to teleport anywhere, and having a steep fee.
hNPC's ranged attack
hNPCs don't use their ranged attacks. (Fighter types are supposed to have them.)
trainers names
The teacher of Elemental is listed as Ollinn Docor in the autonotes, when you meet him, you find his name is Peterk Oiln, same with Dark - Tlac'aelel Klinda is actually Bohus Kinar. (contribution by GazDone.)
banker NPC
The banker NPC also gives you 20% bonus when withdrawing money from the bank. This in effect gives you unlimited money (with some patience :-)) (contribution by Josh Harding, although known before)
Items of Permanence
These can break in inventory anyway (perhaps only if unidentified?)
Items disappearing
unequipping an item while your inventory is full will cause item to disappear (it seems to stay equipped, but change away and back to character, and it's gone). This also happens when a broken item is unequipped automatically. (contributed by Mike Kienenberger)
Black Chests respawning
Some black chests respawn as soon as you re-enter the dungeon (Training Hall, Dragon Cave, Lich Lab).
It is debatable whether this is a bug, because you can't find artifacts from random encounters, so if no chests would respawn, it would be very improbable to complete an artifact set. On the other hand, once you've collected some 50 artifacts, the game starts to lose it's challenge.
Compass
The compass in the upper right corner doesn't work well; it often points to different directions than you expect, and then it doesn't match with your location arrow on the automap either. Just don't look at it, and use your map for directions.
Stuck in map
There are some places in the maps where you can get stuck.
Crashes when entering area
Sometimes people keep getting crashes when trying to enter a certain city. Deleting the minisaves of that city usually helps. (See here for details.)
Combat feedback
Miss in melee combat looks like a hit anyway (bloodspat, monster groan)
Combat gem
The hostility indicator sometimes stays red when you run away from monsters, even long after they've given up. Leaving the area can be the only thing that helps. This happens to me often in Frosgard, where there seems to be an ice lobber stuck in a wall near the ice cave, that can shoot at you, while you can't kill it.
Infinite Attack bug
A direct quote from a post at Telp's Tavern:
"When you have a couple of NPCS in your group (at least 2 now) and I cast the Haste spell, if I go into the single round fight mode then it will go to them and suddenly ONLY switch between those NPCs. So effectively you have an infinite number of attacks from them before anything else can act."

Quest and Dungeon

Promotion quests are single try
Once a promotion quest is done, you can't go for it again. If you're caught by this, you can use Dan Hawkins' MM9 promo editor to fix this (see links section).
Quests in multiple parts
Promoters do not conform single quests; only when all are done will they acknowledge.
Priest Promotion
the new priest in Lindisfarne says you'll meet in Guberland, but you never will. (Just complete the other quests to get your promotion) (fixed in patch u2)
Puzzles in Turn-Based
You can't solve a number of puzzles in turn-based mode (e.g. walk the flames in Verhoffin's ruins; open the puzzle doors in 1000 Terrors)
Waiting
If you need to wait for something (potion, treaty), you need to spend at least 5 min. resting in the same area. Going away, running around etc. won't help. Only for the abbot of Lindisfarne you need to wait for 10 min, for him to speak with the new priest.
Askram Keep
Many people have had trouble completing this, even after destroying all 8 'hearths'. The only way to complete the dungeon correctly was not to leave it until it was finished. This is solved with the official patch (1.2).
Kluso's house
Flamestryke (find her site at the links page) reports some trouble with not being able to leave Kluso's house after slaying the guard captains. The solution seems to restore the autosave, and then not to rob the guard corpses that won't go away. See her site for more details.
Thjorad mine
sometimes this is a freebie: all dwarves acknowledge you've done their quest when you first speak to them. (GazDone's contribution: "At the entrance/exit, 'using' the middle ore container on the left completes all the quests, the designers have left the test code in.")
Frosgard bank
If you have linking orbs with you, every time you talk to the banker will cost you another orb. So talk to him exactly once for 1 orb, and then not anymore until you've installed the orbs in all other banks.
Frosgard ice cave
There seems to be an ice lobber stuck somewhere in a wall, close to the entrance, that can shoot at you, while you can't hit it.
Dark Passageway
mirrors need to be aimed directly at target (not physically correct). (see the FAQ page for the solution)
Dark Passageway
There is a small passage that leads to a drop into a pool with a Sea Monster. Some people have bad trouble, even while crouching, to pass through it. (see the FAQ page for details)
Verhoffin's Ruins
Lich Lab
1000 Terrors

Artifacts

Here all artifacts are listed that do not show their attributes at the stats and skills screens. Only the differences to the expected effects are listed. Note that there are also a fair amount of attributes not documented. (see the FAQ page for more details)
fragile artifacts
I've never seen fragile artifacts break (Fre's heart, Integris, Sygnir, Blackpowder). Mevan sword does break at the first hit though.
Screever
this artifact drains Xp in stead of rewarding less: DON'T USE IT!!! (see also this post)
Bloodaxe
No Endurance bonus.
Broderick's Gloves
No effect of +2 Vita (?) noticed; gives +2 light skill
Excala Banna
Gives +15 Endurance in stead of -5.
Formanir
Gives 'only' -10 Endurance.
Hubris
Gives AC 20, which I can't match with it's attributes.
Integris
No to hit and damage bonuses visible in stats screen.
Lubricious
No damage reduction visible in the stats screen, or mentioned separately in the combat history.
Mjulnir
No Might bonus.
Samarjit
Gives +80 Might and -20 Speed, next to the mentioned attributes.
Weregild
No Endurance penalty visible in any character's stats screen.

Spells

6 spells are listed here because of their recovery times: all spells have recovery times a multiple of 10, apart from 5 of these, and those 5 values don't neatly fit in. The 6th (curse at normal level) has no recovery time at all!
Not really a bug, but bothersome anyway, is that there's no way to see if many of the beneficial spells are still active; there are icons for torchlight, fleet foot, feather fall, and you can see wizard eye. But not bless, faith, regeneration,... I think all detrimental effects are visible in the quick overview ('Z') screen though.
Arms of Earth
your characters can't get caught in it, in contrast to the description.
GM recovery time looks like a mistake (-,120, 90, _18_).
Bless
GM recovery time looks like a mistake (90,90,60,_18_).
Chain Lightning
Recovery time of at GM is extremely short (-,-,90,_18_, while no other master spell has recovery below 60).
Curse
Recovery time of 0 at normal level.
Divine Intervention
Can be cast unlimited by setting it as the quick spell.
Disease
Spell cost increases with elemental skill without any benefit.
Elemental Aura
Does absorbs damage and doesn't deal it. (mismatch with description)
Enchant Item
Effectiveness decreases from spirit level normal to expert.
Eye of Leggib
Expert recovery time seems wrong ( -, _36_, 90, 60).
Haste
No weakness afterwards, like the description claims.
Lloyd's Beacon
Duration is unlimited (?)
Magic Mine
The formula in the data files is not implemented as specified: now they do very little damage in stead. And they explode after a minute anyhow, in contrast to the description.
Natural Armor
Can be cast by, and on someone in metal armor, contrary to it's description.
Phantom Fighter
Description at M and GM level claims you need magic weapons, but normal will do, too.
Poison
Expert recovery time seems incorrect (90, _27_, 60, 30).
Power Draw
Can only be cast on hNPCs, without any obvious effect.
Regeneration
Always gives only 1 hp per minute (in patch 1.2).
Souldrinker
Can't harm peaceful NPCs in it's area, contrary to it's description.
Transfusion
Can't be cast on character or hNPC (also has no apparent effect).

Skills

learning
At GM it gives 50% * skill level; even if this is meant this way, it's unbalanced.
dodge
Skill bonus at master level equals bonus at GM level.
shield
GM doesn't give bash attacks.
merchant
At high level (>10), a master merchant starts to buy for less than item value, but sell for exactly item value; with values above 30 or so you'll even get payed when training!