The last time something peculiar happened in my Add/Remove Programs it was due to a system cleaner (Spider) removing necessary information from an Index.dat file that is 73K in the Windows folder.
I changed to using CCleaner.
So, if you are using a system cleaner and have access to another XP system, you can search for the location of the file by entering Index.dat in the Search box with the C: drive selected, and replace the file with a copy from the other PC.
If the cleaner cleaned the one on the affected PC it won't be 73K.