Do you use the program " EasyCleaner " ??. That sometimes screws up
the Add/Remove program applet. Give this a try
Go to Start>Run, type in "appwiz.cpl" (without the quotes) and click OK (or
press Enter).
If it doesn't start, you can try replacing it with a new copy through System
File Checker. Rather than running the whole SFC routine, you can go to
Start>Run, type in "msconfig" (without the quotes), click OK and on the
General tab, click the "Expand File" button. Tell it you want to extract
appwiz.cpl, tell it to extract it from either C:\I386 or your XP CD (which
you'll need to put in the CD drive) and tell it to extract it to
C:\Windows\System32.