One thing that happens with P4 and PP is the poser.rsr get corrupted, but a fresh install should have cured that.
However this file does get changed and the uninstaller may have left it in the install directory as the details wouldn't match the original.
So try an install to a new directory or be sure to clean up everything in the install root.

To stop this causing trouble keep a copy of poser.rsr (once you got things set up the way you like) and use it to replace when necessary.