Since your machine doesn't have a "retail" XP, you can't perform possible repair installs of this OS. You'll have to make sure your backup is current then boot the machine's restore CD and start over.
This is quite normal. The OS does not stop people from breaking it.
I admit it...I moved my startup folder from C drive to D and now I am dead in the water. The computer is a Sony PCV RS420 with Windows XP Home Edition with all the updates. When I start the comp. I get "SONY" on the screen and thats it. Unresponsive to all F commands. Any help with be appreciated!! Thanks