I just signed up for these forums to let you know that I was having the exact same problems. Like you, I narrowed it down to a problem with the hard times esp. I just downloaded and reinstalled the unofficial skyrim patch, unofficial dawnguard patch, and hard times and it seems to be working now. My guess is that the problem might have either been caused by installing an older version of the unofficial patch (I just saw that the unofficial skyrim patch was last updated on the 1st, and I think I first downloaded it before then) or due to the skyrim revisited legendary suggestion to delete the .bsl files. Hope this helps. Edit: Just checked, and it's not due to deleting the .bsl files. So my problem was either caused by an older unofficial patch version or some other problem that was fixed by reinstalling.