Intel iMac won't shut dowm

[GreekPastry]

About every other day, when I shut down from the menu, I get an error saying an application failed to shut down and shutdown fails. The application is purely random. I have to then do a hard shutdown. If I run maintenance (Onyx), the problem disappears momentarily but returns within a day or two. Very frustrating. Anybody have any ideas?

 

[BeanieRobert]

Something like that recently happened to me. Safari would randomly quit, occasionally had no finder windows, and i couldnt shut down, sleep or restart. The Mac Genius told me to reinstall Leopard. I did an erase and install and then used Time Machine to get all my data back and since then, i havent had a problem

 

[macgig]

try zapping the pram, see if that makes any difference. Hold down the

Command option P R keys during startup until you hear two chimes.