My computer keeps rebooting on start-up after I tried to upgrade the RAM-memory. I tried to add a 512 mb RAM-stick to my current computer which I took out of and old computer. I didn't think this would be a big deal but apparently it is. After I inserted the new RAM-memory, my computer began restarting continuously, never getting to the desktop-stage...this didn't change after I removed the new RAM-memory, it still keeps rebooting. I'm afraid I may have accidently brought in a virus or something with the new RAM-memory because the rebooting-problem was also the reason why I abandoned the old computer (the one I got the RAM-stick from)...I had the exact same restarting-problem on that computer (I didn't think the problem would be transferable through a RAM-stick)...I tried running windows in safe-mode but this doesn't work, it just keeps rebooting. I also tried to re-install windows and/or run a recovery-program from my windows xp-cd-rom, but this didn't work either...I get a blue screen and an error-message I don't understand... Can anybody please tell me what could be the problem here? Dit I accidentally transport a virus or something? If I didn't provide enought information to diagnose the problem, what kind of information should I add? I'm sitting behind an different computer now and I (obviously) can't run any kind of diagnostic software on the computer that keeps rebooting on start-up.