Mine does also. It seemed to be working fine, until I "healed" a trojan at the recommendation of my AV software. Now it starts to boot up, gets to the logo screen, and then reboots itself. selecting "safe mode" or "last known configuration" doesn't help. I don't have a boot cd. I tried to make one with my laptop, which has the same system (windows xp pro), but it didn't help. Any suggestions?