Maya 5 = buggy
Maya 5 PLE = Who knows...
My guess is it has something to do with either the preferences, the program or your video card, or a combination of the three. If the problem persists, go back to a version that didn't give you any problems. Sorry, but that's about the best advice I can give without knowing more about Maya 5.0 PLE or your system.
Dave Baer
Professor of Digital Arts
Digital Media Arts College
Boca Raton, Florida
dbaer@dmac.edu