When you reopen the drawing have you also checked it out first? You shouldn't have to but might learn something to try it the opposite way. Also try turning on or off the PDM add-in. Try turning back on all dismissed messages to see if there is any help that you have banished. Is it only this drawing or any? What if the drawing is not in the vault? What if none of the parts in the drawing are in the vault? Is it only ordinate dims that cause the problem?
Just some thoughts to investigate.