Welcome! My guess is that you should go into settings-applications-manage apps-all- then select android market. There, try making the selection to uninstall the latest update. If that doesn't work, try clear data...
Actually, do the steps in reverse. If that doesn't work, then pm me or ask the question to folks smarter than I am in the
Motorola Droid 2 - Android Forums section.
PS: I'm running liberty 1.5 as well and love it.

I have a droid x.