I finally got my problem fixed!! I read a number of posts talking about the relationship between the 10.5.7 problems and the presence of an external drive when the update was done. I didn't have an external drive hooked up when I did the update but still had the problems. I did, however, have a USB hub plugged into my iMac. When I unplugged it my problems went away. When I would plug it back in the problems returned. So I plugged it in and eliminated the USB plugs in the hub one at a time and found that I had a D-link for a bluetooth wireless mouse that was either bad or incompatibale. Either way when I removed it everything was fine. I could shut down and restart, etc. with no spinning beach ball. Not sure if this will help anyone but check it out and see.