Seems package location and refrences not up to date.
I will occassionaly find common items not working as in your case.
Sometimes my personal keyboard shortcuts will fail to work while the meta references in the config continue to be in order.
In these cases an update will usually reveal the problem or a dependency and thereby a cure.
Try, as root user of course. Many times will do the trick.
_
eix-sync
emerge -auND world
emerge --depclean
revdep-rebuild_