If I leave mumble on when I suspend my computer (windows XP pro 32 bit, up to date w/ patches), the side mouse button I have set to push to talk doesn't work until I quit mumble and relaunch. I have seen this behavior a few times so I know it is repeatable, but I am not sure if it is completely consistant yet.
Mouse is a Intellimouse optical USB. I have not tried it with a keyboard push to talk key so I don't know if that is also affected. (Just though of that while I was typing up this bug)