Two days ago I ran the latest software update (can't remember what updates were installed) on an iMac G5 running 10.5.5. Now when I boot up the machine, the gray screen comes up with the Apple logo like its supposed to, then a light blue screen comes up. The cursor is displayed for a few moments then replaced by the spinning beachball. The computer will sit like that for a full day without changing. I booted from an OS X install disc and ran disk utility. It came up with repairs and successfully completed them, but the computer is still behaving in the same way. Help!