From what I recall from another such report and its reply, it is something to do with too many spawning critters on that map. Think the reply basically was: Pull Melchior back towards the elevator, fight a bit, go up the elevator, go down said elevator and repeat until he's dead.
(Tried finding that reply I mentioned, but it is past midnight and I'm rather tired already).
(Tried finding that reply I mentioned, but it is past midnight and I'm rather tired already).