my screen freezes and flashes on/off when i click on zip files

have to unplug computer to stop it.. flashes about 2x to 3x a second

ANTEC 900 Case.
ASUS Rampage Formula X48.
Intel Xeon 3110 3MHz Core2 Duo.
VISTA 64bit Home Premium.
Silent Knight2 CPU cooler.
8GB OCZ Reaper HPC DDR2 1400.
2x Western Digital Caviar 500GB HD RAID1.
VisionTec Radeon HD 3870 X2.
OPTI UPS Battery Back Up.
Cosair 750 watt PSU

do you use a third party zip program or Microsoft's built in

if you use the built in you may want to try a System File check

http://www.vistax64.com/tutorials/66978-system-files-sfc-command.html

I'd also try a virus / spyware scan just in case

scanned ok..