I have the same problem using Fiesty Herd 5 on a sony vaio vgn-S1XP. It could be interesting to note that, at least in the case of vaio laptops, there is a general regress in all the functions related to hot-keys (I guess the power button is also monitored by sonypi).
-- Logout screen appears twice [Feisty] https://launchpad.net/bugs/81227 -- desktop-bugs mailing list desktop-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/desktop-bugs