Cannot mount any file system/USB stick with Nautilus side bar after changing UID of my user

Cannot mount any file system/USB stick with Nautilus side bar after
changing UID of my user

There are a lot of answers in here that describe how to change a user's
UID. This is necessary to match it to my NAS and to ease NFS mounts and
permissions.
BUT: I had to do this on Ubuntu 13.04 and after I changed my user's UID, I
cannot mount ANY devices anymore in Nautilus side bar. In Nautilus when I
click on a different file system that is not mounted or insert a USB
stick, I get the error message: (in German)
"Dieser Ort konnte nicht angezeigt werden" and then (I translate): "You
don't have the required permissions to see the contents of
ad390f97.........."
This is a DIRECT implication I got right after changing the UID and
rebooting. So there must be something wrong in Nautilus that does not like
changing of UIDs!
What is that? I need to get this fixed!