Created attachment 5543 
Screenshot of tree view panel

The tree view panel shows a spurious and non-functional
"File System" icon.
Working down from the top the icons are:
Home Folder
Desktop
Trash
File System (spurious)
File System (ok)

The 2nd File System icon is the normal one showing all
my root filesystem folders.

The 1st File System icon is weird:
1. The actual icon is a white blank
2. Expanding the icon leaves a "Loading ..." child item
3. Properties dialog gives all sizes as zero, and owner root

Some system details:
Ubuntu 14.04 LTS
Kernel 3.13.0-30
I have no network mounted filesystems.
I have a single disk with 4 partitions:
   / /boot /home swap
I use an encrypted filesystem for my home dir.
Perhaps thunar is picking up the raw encrypted fs?

This appears to be harmless, but is annoying.

Many thanks,
Ian