Can anyone help with this please?

Since recently installing 12.04 from a downloaded live CD onto my desktop computer, I have been unable to re-establish a network connection with my other local computer in Nautilus. I have once had the following message displayed:

DBus error org.freedesktop.DBus.Error.InvalidArgs:Mountpoint Already registered"

The desktop has a wired connection to hub and the other machine is wireless connected. The latter still connects to the internet OK.
Previously, I was using Ubuntu 11.10 which the other machine is still using.

Samba 4 is installed, but I have since run
apt-get autoremove
and the following is an extract of the report:

dpkg: error processing samba4 (--configure):
 subprocess installed post-installation script returned error exit status 126
No apport report written because MaxReports has already been reached
                                                                    Errors were encountered while processing:
E: Sub-process /usr/bin/dpkg returned an error code (1)
Is there a bug please?? Any comments or suggestions will be welcome, thanks.