It would appear that if the directories /var/lib/samba or /var/cache/samba have anything other that 0755 permissions nmbd will fail to start as the testparm call in /etc/init/nmbd.conf returns a non-zero error code (1).
It would be good to get confirmation that this is the issue (I have reproduced artificially but looking at the number of duplicates against this bug report that should not be a problem).
It would appear that if the directories /var/lib/samba or /var/cache/samba have anything other that 0755 permissions nmbd will fail to start as the testparm call in /etc/init/nmbd.conf returns a non-zero error code (1).
It would be good to get confirmation that this is the issue (I have reproduced artificially but looking at the number of duplicates against this bug report that should not be a problem).