are you using the latest NMM? I believe what it does is make the file read/write for itself, and then reset it back to read only on exit. so, you probably need to reset the attributes manually before using loot. then after using NMM, reset the attributes again, use LOOT again, and then reset it back to read only. ...and don't use the game launcher, just run the direct EXE instead. should work. or, there might be an option within NMM (since Loot is popular) to actually have it look to the LOOT load order tables instead of its default load order tables, in which case you should be good to go.