Do you per chance, have Avast installed? If so, disable it, and your problems go (maybe) away. This is a Unity bug... in 99% of all cases. And with that I mean the error message is a Unity error (Unity is the engine that TLF runs on)
Edit: I had to make my reply a bit more vague because this issue can have many more causes, not just AV software.
PS.: Aside that, just disabling AV software might even not help. For some compatibility mode helped, for some uninstalling the AV in question and reinstalling helped. There was never 1 specific reason why this kind of error popped up. ;(