This bug has been reported on Ubuntu Launchpad as:
  https://bugs.launchpad.net/bugs/164120

From the ubuntu bug:

I am using a laptop which I use to in home and office. At home I am having network drive which mounted through nfs in home.

I normally put my laptop to suspend and then bring over the same to work. When I access the file manager in this case, it just simply hangs it does not open any folder neither from Places or directly typing command nautilus.

This is very annoying as I have to reboot the computer just for the file manager hanging.

Comments from cjk@teamcharliesangels: 
This bug appears to be present in Nautilus, Thunar, Dolphin, and Konqueror. Comments through the bug report indicate it happens with all the file managers. It has been ruled out as nfs-utils causing the issue.