I recently tried to play Morrowind, and something I've never noticed happen before happened. Whenever I went inside, my turning screwed up. I move my mouse as fast and far as possible and still it only moves a small amount, and it appears to lag as if I have a really slow computer (I don't , it runs Skyrim okay) but this does not affect moving with the directional keys, which looks normal. It makes the game nearly unplayable, since lots of things require going indoors. The only mods I have are Tamriel rebuilt (currently not activated) and MGE. Nothing, as far as I am aware, that should mess with the game mechanics. Anyone know what my problem could be?

Having the music turned down to 0 can cause lags in interiors. If you don't want the music, just put it one notch to the right - you still won't hear it, but it should fix it.

Hm, I think I have the music on still. And it's not really lag I think, just stuttering, I guess is the word to use, that appears like lag, when I turn. Like trying to turn a lever that is somewhat stuck, it moves in odd jumps.

Music doesn't have to be turned off for this to happen. The game sometimes stutters when the volume is low, too. Turn it up =)