7800GS Problems

I heard that this can solve artifacts, or in your case, strange colours   .

go to:
Start >> Control Panel >> Display >> Settings (tab) >> Advanced >> Troubleshoot (tab) >> ENABLE WRITE COMBINING

If Write combining is unticked, tick it.
If it is already ticked, untick it   Sorry i can't remember which way it works. All i remember is that the option changes artifacts and strange colouring on alot of games. If it doesn't work Simply tick it on/off to it's default settings

Yeah I tried that. Didn't do anything. Turns out it was an amazingly stupid mistake. I spent 3 1/2 hours trying to correct it, when all I had to do was push the card in a little bit harder. Thanks for the help though.