Sys Specs Asus P5LD2-VM mobo Pentium D 950 3.4 Ghz EVGA 7900 GTX 512 Mb 500W PSU 1 GB Kingston Ram Vista Basic OK well I guess I will just get down to it then. So Ever since I began building this system I have encountered CRC errors while trying to UnRar or install software. Just to be clear I have checked all the files/disks and there are no errors, in fact when unRaring files it seems to be different files that fail the CRC check at different times. I have tried many things to find the problem here, I have tried all Windows OS's back to 98, I have bought new Ram, upgraded the Video card, new PSU, different mobo updated Bios and even took it in to a "tech" to be checked out. There was no change. So... quite by accident I found out about changing the processor affinity because of some conflicts on old games I was playing. Then I noticed that if I set WinRar to use only 1 processor there were no CRC errors. Of course I would like to use both processors (kinda the idea behind the whole Pentium D) and I cannot always change affinity when tring to install a new program. If anyone has any thoughts on this I would apreciate hearing from you. Thanks !!!