Curious if anyone else has experienced any problems with their on-line statement. I believe my point balance to be correct, but the detail of my stays is not. I had four stays in the span of 10 days in February. All were there one day, gone the next but the balance is correct. An email to their service group got an unconcerned "well, the on-line stuff does some odd things from time to time."

Anyone else experience anything like this?

I have had a very similar problem. All my activity from October 2002 to February 2003 does not show online. It is available via the telephone system. Like you, my total points online are correct.
I also called Marriott Rewards Customer Service and they can see "all" my activity via their system. I received an email from an online services person named Dari S. who indicated that the "Oracle database" (the online database) was somehow not matching "their" system. She indicated that they would manually update my account but that has not happened yet (over 2 weeks ago).
Based upon your posting, I think they have a bigger problem and are not aware of the impact yet!
You may want to call 801-468-4000 and ask for Dari S. in online support and tell her your story.

That is the exact same timeframe botched up on mine. Very odd. Apparently the sum of the parts is less than the whole.? Must either be a display glitch or it's not a relational DB they're using.