When you buy a card (or anything for that matter) second hand, you are buying all the old owners problems. If you want to replace it hope it's still in warrenty and such.
Somewhere around here I might still have an old Ti4200, but I have no idea where at this moment in time. It'll be a huge hit to what you're currently running, but if you need a stepping stone until you can get your card sorted, it's yours if you come and collect it (I might be nice but I'm still lazy).
Faster I'm sorry you cannot play LFS because of this problem really I am but there has been at least 5 threads, hundreds of replys and at least 3 MSN conversations to try and help you sort this out and nothing has even got close.
Your card or whatever it is, is basically ****ed! There is nothing more people here can do, sorry.
I am leaning towards that. I hate to admit when hardware is bork, but by the sounds of things, this is one of those times. All you could really do now is RAM the card, or buy a replacement. This is really why you should never buy second hand hardware unless you know the source well (I have two second hand cards, and both work fine because the guy I was getting them from has spent too long building a reputation to go and screw himself over).
Just so you know, not all hardware dies in one go. I have a gig of ram which started to die a long time ago, would only work on some games, but it finally got to the stage where it was only stable in Windows, and even then it had hickups.
You seem to have very little idea as to what is wrong, from what I've read, all the standard things have been tried, all you're left with is format and get a fresh start (unless you've already done this), or RMA.
Last thing I'm going to say on this because it's taking the piss now.
Either try another card OR back up everything you need and re-install windows.
I don't know what you expect people to do for you now, many have gone way above and beyond. YOU need to sort this out, you’re testing peoples patience and it looks like you loosing yours as well.
Thats not true....the graphic cards use diffrent part of the chip when doing 3D(like LFS,Doom3 etc) or drawing desktop(IE explorer,WMP etc).
I have just RMA my 7900GT a 2 month ago and got a new one because I got exactly same problem.Some games were fine even few hours in other I got stretched textures,colour dots etc.
Guess what...I got new card because the original one was confirmed as broken.
Easy as that.If you have got the card from 2nd hand you got probably a problem.
Just looking at our Czech law which should be in harmony with EU law(dont know if this works in GB)I think everyone who sell something to someone else must provide 1/2 year warranty.I know it sound kidna weird for already used thing but its like that.
Another thing.If someone sold you something claimed that it has no hidden defect but it has you should return the card back to him and ask for money refund(i think the term for this is as well 1/2 year)
If you dont want to format, reinstall windows then Pay a Tech that will for you. if you dont want to do that then all you can do is RMA the card. Contact the company that made your video card and tell them you are having a problem withthe card. Tell them it happens in "Most" games you play.
Dont tell them your the 2nd owner of the card or anything like that. See what they say. They may allow you to RMA it without a problem depending on the company.
And if you dont want to do that, then Contact me and i'll build you a new computer