Put the worst buggy, most God awful games you can think of here. You know the games you dropped a heap of cash on and it won't even load or crashes at a pivotal point in the game or even the dreaded black screen. Where nothing shows up on the screen and it seems to hang in some sort of hard drive loop.
The first one that comes to mind for me is Jurassic Park Trespasser.

Hehe, with my own recent thread in mind, I have to say Knights of the Old Republic 2 ;-)

Daggerfall. It was nice of them to include the console command to let you teleport to the quest items since they could be spawned outside the dungeon geometry or in randomly generated rooms with no entrances.

Stalker. Sorry, Ess Tee Ay Elle Kay Ee Are. - Yahtzee rocks.
Karl

Hellgate London. I dropped $50 on that god awful piece of garbage.

Dungeon Lords - So many bugs I just ended up exploring instead.
The Creed - It crashed so many times I came up with new swear words.
XIII - Great game, just one glaring bug that made it impossible. There was a boss that ran through a sliding glass door and it closed after him. So I was stuck in that boss level forever unable to kill the boss because I was on the otherside of the sliding glass door. The game was an instant frisbee.

Descent to Undermountain. Did I win now?

Sorry guys, just one posible answer: Gothic 3.

I recently tried to play the demo of Splinter Cell: Double Agent. I didn't actually get to the "playing" part, though. No matter what I tried or what settings I changed, it bluescreened about 30 seconds into the opening cut scene, every single time.

Super Power - You click on something wrong it crashes and if you play to long it crashes.

Fallout 3 Piece of Crap Edition.

I can totally understand why you guys would be pissed. I only paid 10$ for it, that's probably why I don't say much. I just had a good time exploring.
Funny, my friend bought me that for my birthday, I haven't touched it. After Gothic 2 and being horrified that it came from the same people who made G1 I didn't want to mess with G3.

Vampire: The Masquerade - Bloodlines, without all of the community patching done. It is so buggy as to be almost unplayable in its default form.

Battlefield 2: Complete Collection. Once you get ingame it works ok (providing your not on vista, then you have truble with mic's sometimes), Its all the messing around i had to do to get in.
FIrst off it has a strange (imo) installer that doesnt seem to know what its doing sometimes.
It installs, i make a account to play around offline and regester my booster packs to it. I dont like the name (can you change it? I dont know) I cant even remember what email i put it under a now im down 2 booster packs. It could be im missing something but man i raged a month later when i found out i had to use that account and i couldent put my boosters on my other account.
Mind you its prolly all a big stuff up on my behalf as i was young when i tried to put it all togeather.