Before you all go "Are you sure it is The Underground 2? 'cause it could be..." YES, I am sure. I had this problem before, took it out of my load list (and that was the only thing) and it worked. I also have not had any problems with any of my other characters who have not tried to do the Underground main quest. The problem I am having, is I CTD every time I try to load a new cell. It doesn't matter if I go to an outside cell or inside, nor if I use a door or the console. I do have the latest version (v7) of The Underground Patch Project enabled in the stead of the standard esp.

Edit: I noticed as a loaded it (winthout Yes to All), that it said it was missing a few global references were missing and the blood drinks weren't found on the ogrim bartender. I will try to write them down later. I need to go to work now.

Have you already completed the Vladir's Crypt quest? There is a bug which causes the game to crash upon loading a new cell 72 in-game hours after completing it.

It can be fixed by opening your save up with http://planetelderscrolls.gamespy.com/View.php?view=other.detail&id=52 and deleting the references to the Vladir's Crypt cell.

Well if you've got missing globals and items, you've likely got a corrupted savegame. I'll wager you added the new version of UG2 in midstream of a game in progress, is that the case? If so, be aware that the original version and the upgraded version are completely incompatible. You can try repairing your savegame with Wrye Mash or some such. You might be forced to start a new game ensuring that v7 is the only Underground loaded (except for the Sanity Globe patch which can be loaded after).
Otherwise, I can't see why you'd be having such corruption. How far along in the game are you? Anyone else with a similar problem?