Same problem here.
I have the same problem even updated to LR4.4 and this is VERY annoying.
i can reset it by restarting LR, but after sometimes, it appears again and you will never know when!!
It is very frustrating specially whn you do a lot of tweaking on a photo, after that, you try to undo a small step. BAM! POLAROID BLUE FILTER. and you are done.
sometimes even Exit does not work, it put a tick near exit and did not do anything.
it is simply not the problem of shortcut string. it is a problem of the panel.