Quote from StormFXNope. But I did find a way to reproduce it. Reset the current profile. Once that's done, not even a reload or switching profiles will do anything. You have to close the game and delete the saved var files. Not sure if it's related to not having dualspec installed.
Bleh, I need to stop being lazy and just go through the code and see if I can figure out what the problem is. >.<
That's really weird. The gray tabs mean it isn't starting up properly, but in the past that has always been because of a lua error (usually referencing nil because some part of the saved vars structure was missing). I can't think of why it would fail to start but not have any errors.