I have a 1GHz TiBook running 10.2.3. A few days ago, it wouldn't sleep as it normally does per the Energy Saving settings. Thinking that the pref setting may have been damaged, I logged out and logged into 'Guest' account to test and see if it goes to sleep by itself. It did.
So I went back into the primary user with the intent to fix it. The phone rang so I chatted for awhile and noticed that it went to sleep. I was a happy camper as didn't have to fix anything, so I re-adjusted Energy Saver back to the usual settings. Again, it wouldn't sleep, so I repeated what I did in the first step and voila, it works (be sure to let it sleep first in other account). I don't know why it happens, but it does sleep right away when I close the cover.
[Editor's note: If you're still having sleep issues, this may help you resolve them. On our iBook, the sleep problems vanished with the 10.2.2 update...]
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