thats probably the new log in string from base-files.
after a reboot everything should say Ubuntu 6.06LTS
** Changed in: linux-source-2.6.15 (Ubuntu)
Sourcepackagename: linux-source-2.6.15 => base-files
Status: Unconfirmed => Rejected
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Wrong (different) dist name after tty logout
https://launchpad.net/bugs/45922