I have a problem with a desktop PC shutting down on windows start up. This started Saturday, 2-16-2013 when windows did an update. After updating, windows automatically executed a restart. On restart, after entering my password, the desktop screen displayed for a few seconds and the computer shut down. I restarted the PC in safe mode and the computer started up. I then shut down and restarted under normal start up and after entering my password, the desktop screen displayed again and the computer shut down. I started the computer in safe mode with networking and was able to get signed on and also get on the internet. Thinking there may have been a problem with the update, I did a restore selecting my last windows update on 1/29/2013. This didn't do any good. Under normal start up, the computer shut down after entering my password. This time it didn't get to the desktop screen. I signed in under safe mode and selected an earlier date to restore from. I got the same result. I then decided to do a recovery from my recovery disks I got when I purchased the PC. I selected to do a reformat and restore to original factory install after doing a backup to an external drive. Everything appeared to load properly from the recovery cd's and I got a message to remove the cd and restart. On restart, I got the windows startup screen where I had to enter a user name, password and password hint. I did this and got the next screen where I selected a background screen. The next screen had me choose how I wanted windows to run on startup. After doing this a got a screen where I selected finish. The screen cleared, displayed a message that I didn't get to read completely, but was something like windows was checking something, and the the computer shut down. I tried signing on again in safe mode but got a message that I can not start in safe mode. Additional attempts to sign on result in the computer shutting down after completing the windows set up steps. Any ideas would be appreciated.