Mario you mentioned the following in comment 9:
"b) If Network Manager calls update_etc_hosts at the exact same time that oem-config was changing the hostname, you can run into this scenario. OEM-config shouldn't be changing the hostname at all in the first place though as there is no place in the UI to set it."
and the changelog indicates:
"* Do not try to configure networking in oem-config (LP: #471498)."
Shouldn't the fix in ubiquity avoid this particular situation? Has anybody tested with the version of ubiquity in lucid or karmic-proposed?