What happens if your computer refuse to load in windows you can solve that by restoring your computer to earlier time in command prompt also through Sytem Restore take a look how to do it.
* Restart your Computer press F8 button on initial startup.
* When you see Advanced Options Menu ,select Safe Mode with Command Prompt option.
* Select the WindowsXP Operating System .
* Log on With Administrative Privilages and in the Command Prompt type C:\windows\system32\restore\rstrui.exe