windows xp wont start

Okay, I am trying to repair a computer with a windows xp home edition installed on it. When i hit the start button it starts and gets the screen where you can choose which account to log on to. You click on the account and it looks like its going to start but then its says saving your settings and goes back to the previous screen. I tried to start in safe mode and I get the same result. I tried last known working configuration and doesn’t work. I tried booting from the xp installation disk and tried to repair. And still no luck. I thank you in advance for any assistance you can give.