My guess is your computer's Path statement got messed up.

To check it open a Command Prompt and type: Set <hit Enter>

You should see included:

Path C:\WINDOWS\system32

To edit the Path to correct it select Start, right click My Computer, select Properties. Next select the Advance tab, and Environment Variables button, and select the Path variaible listed under System Variables.

When editing it should include:

%SystemRoot%\system32

Which translates to something like:

C:\WINDOWS\system32

Each entry included in the path must be seperated by a semicolon.

Good luck.