During the quest Waking Nightmare where I had to drink the potion in the tower above Dawnstar, I get all the way to were I have to bring down the barrier by removing the soul gem. Every time I do this I crash to desktop. I even crash when I try to save before touching the soul gem. I have a save right before I release the miasma but that's as close to the crash as I can get. Please help, I'm really trying to finish this game before I start a new game and this is frakin frustrating. (pardon the bad language)

This is a known bug caused by the 1.8 patch, It's impossible to save after you drink Vaermina's torpor, and before the quest is over.

There is no fix, or workaround, that I am aware of. You just have to finish the quest without saving.