You could try the pause break key
If it is recentStart 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.
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
Look for a system restore point, or just before you installed anything which may have caused it