I've been having a problem with PowerPoint for some months now. I can edit and save .ppt files but PowerPoint crashes every time I go to close it down. The error message is totally useless ("a problem caused the program to stop working correctly" - yes I know!!). For the same reason I can't view .pps files at all.
I have MS Office 2007 and have tried uninstalling and re-installing the full set of software but nothing has changed. I can't think that I installed any other new software around the same time that PowerPoint started giving me this problem.