First of all, to be on the safe side, ensure that you back up all your data and settings.
Some suggestions - by no means exhaustive:
Try leaving it running overnight - if it still doesn't populate the list then move on to next steps!
Search Google for
"Add / remove programs" empty
and see if anything seems similar. Some of the suggestions might work.
Get hold of a registry cleaner to identify and fix orphaned registry settings.
Run "Hijack this" to identify if there are still any nasty processes that shouldn't be there.
If you can't identify the problem to fix it, you can try a
Repair of the Windows installation. More
Here.
If that doesn't fix it, you might have to do a clean install - just as well you backed everything up!
SD