You can run the System File Checker tool to scan all of the protected files on your computer:
Click Start > Run and type: CMD , and hit enter.
In the open box, type sfc /scannow (including space) and then click OK.
Note that you may be prompted to insert the Windows XP installation CD.
Then perform the following maintenance suggestions:
I have entered CMD command & then typed a sfc/scannow as you suggested but
all I get is the following message 'sfc' is not recognized as an internal or
external command, operable program or batch file.' I have also experimented
in trying putting the space at various points along this command but I
always get an error message. Any other ideas?