squebel, that's the exact scenario we are in as well... to the letter on every front.
I've followed the various KBs and deleted all the rollup jobs and recreating them using the sql jobs found directly in the 5.0-Update 2 install and that didn't resolve the problem.
I'm currently in the testing stages of our 5.1-Update 1 upgrade and already see MASSIVE changes to the SQL structure that I'm hoping makes all this a moot point; but, it's still going to be some time before I can get there in production.