I downloaded KGPanels before 3.3.3 (on its own and not part of a UI bundle), and it continued working after 3.3.3 launched; however, I may have updated it prior to playing after 3.3.3 hit. But you say you already updated it and still it doesn't work?
I would suggest completely uninstalling the mod and then reinstalling from scratch. Note that when you uninstall the mod, the settings files still remain and must be deleted (the problem could be corrupted settings). If I remember correctly, they are located somewhere in your WTF folder, if you dig around in there, you should find them. Make sure those are deleted as well before reinstalling KGPanels.