problem with samba in Ubuntu 9.1

[helmut niko]

I am running Ubuntu 9.1 as a guest system using VMware Fusion on an
Intel iMac. Everything seems to work except when I press the network
button in the places menu. It leads me through network name, pressing
that one it leads me to the workgroup name, however pressing that one it
gives me the message failed to mount shares.

For those knowledgeable with VMware Fusion, I am using the NAT option
meaning that the guest system is sharing the network adaptor of the Mac.

Grateful for any ideas.