To start off, I had this problem when I had windows xp sp2 installed as well. I read that there were security issues which I thought may have been the culprit so I formatted, but to no avail. As the subject suggests, my computer randomly stalls and reboots itself. This has never happened until I bought a brand new western digital hard drive from fry's. I thought that it might have been my power supply and that it could not cope with the additional hard drive if it was at peak usage. I changed from a 300 to a 400 watt PS, but the problem continues. Only options I have left are maybe bad ram or faulty hard drive (even though it's new) which is why i'm having a hard time accepting that. Before I spend money on anything, I'd like to receive any other opinions/solutions/advice on my current situation. thank you in advance

check event viewer for any system or application errors during the time of reboot way you get there is you right click on "My Computer" and then click on "Manage..." then look for "Event Viewer" then double click on "System" or "Application" and look for red circles w/ white X's

Hi, If u remove the new drive completely will the machine run stable.Check the jumper settings on both drives old & new .Confirm that they are correct. Is the new drive a master or slave.If it is master remove any slave devices if any.Check WD website for any diagnostics.Chech that the bios supports the new drive.Can you run the new drive in a different machine or can you run the new drive as the boot drive with old drive removed?