[emmaylots]

It's quite strange. Anyway, I will advise you to install an Open Source edition on ubuntu 7.10, to see how it works.
You may need to edit the /etc/lsb-release and rename the /etc/debian-version, before running the Zimbra install script.
The lsb-release is to be changed to 6.06 instead of 7.10.
You can get the Outlook migration wizard and the Exchange migration wizard as well from the new installation, only make sure it 's the same version of Zimbra you intend to run.
Furthermore try and reinstall Zimbra on a test system running 8.04LTS.
If the problem persists, you may need to report the bug.
Cheerio.