It's happen on my Katya too. I'm using
Katya 32bit kernel 2.6.38-12-generic
ASUS 1215B AMD E-350
Radeon 6310 with ati catalyst 11.10.
It just happen, not after update (mean I'm not update anything from a week before). Been googling it and still got confuse.. It's annoying to type "sudo halt" everytime I want to shutdown my laptop (not always but very often)
Not only mintMenu have a broken shutdown button, but also gnome main menu, menu bar, and GnoMenu. Hope anyone can help.






