My character's eyes and eyebrows/forehead keep twitching back and forth (The race doesn't matter) every few seconds. It looks as though their eyes are trying to move but it doesn't quite happen. I'm getting this error on both vanilla Skyrim and a heavily modded version. I Googled it and nothing came up, so I'm at a loss now.

Re-install Skyrim that way:

First do a standard uninstall. (Control Panel\All Control Panel Items\Programs and Features-> Uninstall The Elder Scrolls V: Skyrim)

Next, delete your skyrim folder under C:\Program Files (x86)\Steam\SteamApps\common\

Then delete your Skyrim directory under Documents\My Games (backup your saves but, just try on a new character)

Then under C:\Users\[Your Username]\AppData\Local\ - Delete the Skyrim folder that is in it.
(You should enable to see the hidden files under windows to delete that folder.) HOW: (View - Options - Folder Options - View - Advanced Settings: Show hidden files, folders and drives)

Go to your Steam folder. Delete the folder named appcache. (Important)

Use Ccleaner after all this (http://www.filehippo.com/download_ccleaner), Go to the Registry tab and hit -
In the Options tab go to Monitoring and uncheck: Enable System Monitoring and Enable active Monitoring

Reboot your computer (Important)

Then install your game again, from scratch. !!!!

*** You don't need to uninstall Steam. ***

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Also move your mods in another folder, and uninstall any (mod) manager you have. (so just clean vanilla skyrim)

After that, verify your game cache files too: https://support.steampowered.com/kb_article.php?ref=2037-QEUH-3335

Revert your GPU settings through your GPU control panel, to default.

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Computer specs ???