I know this isn't much help, but this used to happen to me A LOT but it just randomly stopped one day and haven't seen the issue since. Worth noting that I've reformatted my computer since then so that may be related but I'm not sure because I stopped playing Skyrim about 2 months before I reformatted and picked it up again a few days ago. I'm using a GTX 590 which is technically an SLI card. That may be the source of the problem, but I would put my money on bad drivers. AMD (ATI) isn't known for their amazing drivers, and I was using beta drivers when I had this problem for my card.