This normally only happens for observed hands - occasionally we don't get complete information about a hand via the memory grabber that PT4 uses to generate observed hands. It can also happen if the big blind is posted and everyone else sits out, but you shouldn't see it for your played hands which actually took place.
But the issue for me is the fact that is crashing with the importing process, i´ve created a couple of new DBs and whenever that messages popups up again PT4 just stops importing....thoughts?