I was able to upgrade my pc without any issues, I think this may have been an issue with syncing of mirrors and updating the list on your pc. the version in the archive is thunderbird_3.0.4+nobinonly-0ubuntu4_i386.deb and the versión update manager is looking for is thunderbird_3.0.4+nobinonly-0ubuntu2_i386.deb.
It must have been an issue with servers syncing. It is suggested to wait a few days for mirrors to be less crowded before atempting an upgrade.
This is more of a support question than an actual bug
I was able to upgrade my pc without any issues, I think this may have been an issue with syncing of mirrors and updating the list on your pc. the version in the archive is thunderbird_ 3.0.4+nobinonly -0ubuntu4_ i386.deb and the versión update manager is looking for is thunderbird_ 3.0.4+nobinonly -0ubuntu2_ i386.deb.
It must have been an issue with servers syncing. It is suggested to wait a few days for mirrors to be less crowded before atempting an upgrade.
This is more of a support question than an actual bug