I have had that happen sometimes but not with these two programs. It's seems that these programs share some general dll files on your pc and when you install or upgrade something they start to argue with each other. Usually it can be fixed by reinstalling the conflicting program (which for you would be Paint Shop Pro). When you reinstall PSPro it will rewrite all the paths to these general files and this hopefully will fix the conflict. And yes, it is a pain in the you-know-what.
Let me know how it goes....
