I had the exact same issue. Finally, tonight I went through and disabled everything, then loaded an old save and started enabling groups of mods until the problem re-appeared. For me, the RaceMenu mod was the culprit; disabling it immediately cured the problem. Looking at the mod page, it appears to be a known issue that I simply overlooked. Hopefully they'll fix it at some point, but until then I'm thinking that the mod isn't something that gets used every day, so I just disable it. It seems like they have fixed the issue. But they havn't released the verison yet. See mod site for info http://skyrim.nexusmods.com/mods/29624