Comment 1 for bug 754618

I have encountered this exact issue also, and also on a machine where I am using an encrypted home directory. Rebooting does also make it go away when it happens; simply logging out and back in is not sufficient to do so. It was also a newly installed system, so there was not much that yet had been tweaked or configured. Next time it happens I will see if there is also any log messages. Particularly I suspect maybe it is some issue with fuse mounting on top of ecryptfs.