I'm going to take a guess that you have spybot installed. Uninstall that and Adaware then take Grif's advice at http://forums.cnet.com/5208-6122_102-0.html?threadID=328220#2968150

Yes it could be hardware. I've lost count of where the owner says it worked fine for months and we find the BIOS was not set correctly for the memory installed. How do you explain that to them?