Had some issues sharing a windows host directory with my Ubuntu 11.04 VM on VMware 6.5.5 – kept coming back with a “Unable to update run-time folder sharing status: Unknown Error”, which was unhelpful to say the least.
I’d previously followed the instructions on installing VMware Tools so I expected it to just work. After reinstalling and still getting the errors, I found some additional instructions on building and installing the hgfs module. After apt-get installing open-vm-source and running module-assistant to install, rebooted the machine. Enabling folder sharing from the host didn’t seem to give any errors, and the folder was able to be loaded.