If you click start then run, type regedit and press enter, then get nothing, try typing regedit.exe then pressing enter
Or, click start, all programmes, accessories, command prompt
AlsoClick start then run, type sfc /scannow then press enter to replace the system files, you need the XP CD and get a blue progress bar, reboot when the bar goes
AndStart the System Restore tool at a command prompt1. Restart your computer, and keep tapping F8 during the initial start-up until you get options, select Safe Mode with a command prompt then press enter.
2. Log on to your computer with an administrator account or with an account that has administrator credentials.
3. Type the following command at a command prompt, and then press ENTER:%systemroot%\system32\restore\rstrui.exe4. Follow the instructions that appear on the screen to restore your computer to an earlier state.
Look for a recent system checkpoint to restore from
For additional information about the Safe mode with a command prompt, click the following article number to view the article in the Microsoft Knowledge Base:http://support.micro....com/kb/315222/
A description of the Safe mode boot options in Windows XP
System restore should run from help and support, it would be blank if it was not turned on, though you should get a message asking you to turn it on