I’ve used a Mac just once in a while when my PC was down. But I have seen that “beach ball of death”, and in my experience, once it appeared, that was it. I had to shut down and start up again.
From what I remember, it occurred at various times, but if I was ever on the computer at midnight, it would appear at that time for sure. Anyone know why - does Apple have some sort of programming to update or reinitialize at midnight or whatever?
The beachball I’ve seen has been the same as the XP hourglass: sometimes a second or less, sometimes a few seconds.
I’ve never seen the beachball on a Mac as a continuous, extended thing. XP Hourglass neither.
Mac OS X uses a Unix utility called "cron" to schedule periodic tasks like updating log files, file maintenance, etc.. cron can run those tasks daily, weekly, monthly, etc. in the "background". Generally, the user is unaware of the background activity, but you noticed it apparently due to the pattern of when the beach ball was occurring.
It's possible that you might find some clues about the problem by checking your log files. The "Console" application - in the Utilities folder - allows you to look at the log files. In log files like "system.log" and "daily.out", you may find some entries that tell what was going on when the "beach ball of death" occurred.
In my experience, the most common cause of the beach ball is Internet communication errors combined with bad client-side scripting. But it may be possible to get past the beach ball by clicking on the Finder desktop, then using the "Force Quit" command under the Apple menu to terminate the frozen application.