Mods randomly uncheck from Data Files

[Zentennen]

When I enter Data Files and check a mod (tick the box to enable it), and then exit; it randomly "unchecks" itself. This doesn't happen every time though, sometimes I check it and it stays that way. Then I try to check more mods, exit, and everything is unchecks. Sometimes some mods are unchecked and some are. I've tried some solutions I found through google, nothing worked. I tried:

 

Going to SkyrimPrefs.ini and making sure bEnableFileSelection=1 (it already was)

 

Disabling UAC

 

Going to plugins.txt and adding the mods manually (the same thing happened, sometimes they uncheck, sometimes they don't =/. Strange because it's just a text document)

 

Disabling "read only" to the 3 skyrim folders (Windows doesn't even let me disable read only for folders for some reason, tried googling this too, no help)

 

Using a mod manager:

I used NMM and it worked fine, until I exited and reopened it, when all mods were removed from the "plugin" list.

 

Any tips on what to do?

 

EDIT: Solved it, I had an old version of NMM.

Edited June 11, 2015 by Zentennen