All great ideas but
None of these have worked for me. I don't use nor have a MobileMe account. What I did notice was the "Events" on the pad are there however they contain very few of the photos that should be there (prior to the recent re-sort only a single event was there, of 10 or so selected). Within iTunes they are still duplicated and randomly sorted. Also the events as seen in iTunes when checked do not have the correct quantity shown on the right side of the pane.
What I did was check all events of the same name (about 10), some had 6 images, others had only 1 image. When sync'd the Pad shows two Events of the same name with a single image in one and 6 in another. Of the 10 or so Events that I checked only 2 showed on the Pad.
Was there possibly something else that might have prompted your solution?
or
If I got a MobileMe account and then removed it, would this likely be a solution? What happened when you restored MobileMe?
iPad1, iPhone 3GS & 4, MBP17.2009