http://discussion.autodesk.com/threa...hreadID=520311
They discuss it here, but they offer no solution.
They seem to think it's a memory issue.
I can only suggest finding a scene that gives you the bad buckets every time, then turn a machine off until you get rid of the buckets. Reinstall Max fresh. Re-render. If it still happens, check the hardware/memory.
Good luck.