Originally Posted by NullWolf
If its rebooting, chances are you're getting an error you can't see.
First thing to do is press F8 before Windows boots to get the Boot Menu.
Select "Disable Automatic Restart" and see what error you're getting. That will give everyone some idea of what your actual problem is.
You can also try selecting "Last Known Good Configuration" on the boot menu.
I tried that, when I go into it I can only highlight "Microsoft windows XP professional" so I press enter and it reboots and it doesn't give me a message before it restarts just keeps doing what it's doing before. And I cant actually get into windows. I needed to phone microsoft for a new product key because mine was invalid so when I went on the internet with my other pc (one i'm on now) to find there number then after I got it and set the new comp back up it just kept rebooting after the windows logo and blue bar.
EDIT: I also tried last known working configuration and it still does the same thing.