hi
 
this is the main menu of Test Drive Unlimited !

 
this is an screen shot while playing...

 
 
also The Witcher looks like this i've ran BioShock too but it was fine !    
this game was working fine last night ...
i had this problem already but at that time i didn't know the reason so i ended up in reinstalling windows
now got a clue...
i've installed and uninstalled Ati Tray Tools today and i met this problem again
i've reinstalled ATI Catalyst and also i've used System Restore to get rid of this problem but i wasn't successful...
 
OS : Windows Vista X64 Ultimate SP1
Catalyst Ver : 8.3
 
 
please help    
 
P.S. : i haven't Overclocked or anything else

i've solved it myself
i had to install an older Catalyst !