In the quest "Hunting the Monster" given by Gunmar, the location given is Morvunskar. The Quest asks that the player kill the Master Vampire in the bottom floor of Morvunskar. It's relatively straightforward, except that the Master Vampire gets up on the wrong side of the bed, and glitches out of the map, making it impossible to kill him.

Any help people?

That's a radiant quest; no spoilers about it. My suggestion is to do whatever you can to kill him before he gets out of bed, I'm sure if you stockpile potions of fortify weapon and use a sneak attack, you can eventually come up with a winning formula.

On, a related note, I got a radiant quest for the Ring of Beast that sent me to the same cave where you complete the drum quest for the Bard's College. My character has already cleared this cave. The chests and enemies have restocked themselves, but the dungeon chest does not have the ring in it. Instead, the waypoint points to the grate you can open to return to the first room. The ring is not on the grate, however. I think it was supposed to spawn in the dungeon chest. I'm slightly miffed at this but I already have the other ring which I would want to use anyways. I just wish I could complete the quest so I could do others.

Erm, as to the 1st issue, I suggest you get an area-of-effect spell/weapon and hit it right next to the wall where he dissapears, that might hurt him, if not, reload before he got up, and sneak so he doesn't wake up or hear you.
Try to kill him fast before he bugs out.