I get the problem as well, every time I run into a mod that freezes the game and uninstall something trying to figure out which mod I end up with FNIS saying it can not find the path for the temp directory. I tried installing directly into the game data folder, but MO would give me the error trying to run it. I uninstalled and reinstalled and it works, but it has worked after restarting MO or my computer, so I will have to see if it remains working while I find the bug(s) in my mod list. Sorry to bump an old thread but this was the first I have seen that doesn't just tell me how to install it.