the problem is not with the rig , its with the drivers..download latest drivers for ur card..
this problem usually occurs while watching movies if there's a conflict
installing latest drivers will solve this issue..and do not install beta drivers , if any
and download drivers from nvidia.com
For vista 32-
*us.download.nvidia.com/Windows/175.16/175.16_geforce_winvista_32bit_english_whql.exe
For XP-
*us.download.nvidia.com/Windows/175.16/175.16_geforce_winxp_32bit_english_whql.exe