Like I said previously: Isaiah Washington and Patrick Dempsey are 2 stupid yentas bored with life and looking to knock scrotums together, because this how they think normal people live their lives.
According to the National Enquirer (and other sources), the fight broke out over Isaiah Washington’s problem with certain cast members being constantly late on the set. It seems that Washington said something to one of the cast members (T. R. Knight) about their lateness, which is when Dempsey told him to pick on someone his own size.
So Washington shoved Dempsey around a bit and then grabbed him into a choke hold. When T. R. Knight screamed at them to break it up, Washington stormed off the set to his trailer (but not without calling Knight a bitch). The crew waited around for an hour waiting for shooting to resume and Washington to come out of his trailer.
Well la-dee-daa! Get a life you idiots!