I use Growl mostly for email notifications because post the Mac OS X 10.5 update IMAP flag support (new mail notification) blows. Unfortunately x2 GrowlMail (the mail notification which I love and rely on) did not work with 10.5 – so I am forced to rely on having SquirrelMail open so I can see what new mail is where within my many mailboxes. Anyway – I recently saw there was a new(er) beta available for Growl and all was working as expected until I downloaded Mac OS X 10.5.3. After that – I had a lot of weird errors and most notably – the inability to restart without physically pressing the power button until a forced restart took place. Finally – tonight (this morning) I did some research and found that other people were having the same issue and everyone with this same issue all came to the conclusion it was because of some startup item (System Preferences > Users > Login Items). Sure enough – after disabling Growl on startup, my computer restarted without any issues. Phew. Tech support is bad – but worse when it costs you time (and then money because of lost time).