Strange intermittent freeze issue. I'm at wit's end.

Sound continues to play while everything else locks up. The second link is a pretty extreme example of the issue; usually, it'll lock up for 5 seconds every minute or so.

Video 1. Pretty tame. Video 2. Extreme example of the lockup. It's very frustrating.

This isn't the only game this happens in, but Bethesda games tend to be the worst for it. I'm running on an Intel i7 975 with a GeForce 560 Ti, 6GB RAM. I do have a lot of mods installed, but even when I only had a couple, this issue occurred. Has anyone experienced anything similar in Skyrim or other games? Does anyone know how to fix it? Does anyone know what the typical cause of these types of freezing is?