You haven't said which Windows OS you are using.
If you're using Windows XP or Win2000 you may need to be logged on as an Administrator.
If that doesn't work try downloading and installing TweakUI for windows.
For some reason, most of the programs listed in the add/remove programs tool don't give me the choice to change/remove the program. This is true of any program installed prior to 10/3/04. Did I accidently delete some critical files, and can anything be done to correct it? If not, how do I remove a program?