Did you run Software Update until there are no more updates to install? There were quite a few between 10.5.2 and 10.5.5

Once there are no more updates to install, restart your computer in Safe Boot Mode. Apple says "Hold down the Shift key immediately after the startup tone and release when you see the progress indicator (looks like a spinning gear)." http://docs.info.apple.com/article.h...db_strtup.html