i have recently yprade my vga card from 5770 to 6850.
since i made that change,at forst boot nono of my usb work at all!
i delete the upper filter in registry and then usb work!
since then i have bsod with this
i have test memory with memtest and all is ok.
i have unistall ati drivers and install it again,but same again.
make cmos reset,nothing.
sfc /scannow,none problems.chkdsk,none problems.
i have one bsod a day,mostly while i am on internet!
never while playing games!