Hi dumbldore. There's nothing stupid about trying PaintShop Pro. The only stupid thing is that the uninstall utility didn't complete the job.
Try downloading RegSeeker click here. Unzip the downloaded file to a folder of your choice (I created a folder that I named Regseeker for this purpose). Then run RegSeeker by double clicking RegSeeker.exe. Click on "Clean the Registry". All the items in green can definitely be safely removes, but I have never had problems deleting the red ones as well. As long as you have a tick in the "Backup before deletion" box, you can restore any removed entries later. Hopefully this will remove the unwanted residual registry entry.