You may have to do this one application at a time. Before modifying the registry, be sure to create a backup the registry using one of these methods:
1) Click on START - RUN and type: Regedit (press ENTER). On the menu bar click on file, then export, choose where you want to save it, then enter a name for it in the box titled: File Name. At bottom put a tick in "All", then click on save. If you ever want to restore the saved version, just IMPORT it.
2) System Restore (it should save a copy daily, but you can always create a restore point manually.
3) The best method, in my opinion, is to download and run ERUNT. It's the best registry backup utility available - and it's free!!!
Okay, now to fix the problem:
Start - Run - Regedit
Navigate to: HKEY_LOCAL_MACHINE \SOFTWARE \Microsoft \Windows \CurrentVersion \Uninstall \<Program Name>
In the right-pane: Double-click NoRemove (REG_DWORD) and set it to 0