(This is the same fix as from UD1 but I thought I'd pass it along for those who aren't familiar with it - I can't find the original thread where this info came from so if someone who has better search skills than me can find it I'd love to give credit for the info to where its due)
First of all make sure you got another launcher installed before doing this since you are in essence removing Launcher Pro so you can install the newer version. Plus you'll need to do this as you'll be rebooting the phone once you do the fix and UD2 only comes with Launcher Pro.
Now for the fix....
Go into Root Explorer if you have it. If not its worth getting since its very useful for moving files around, deleting files, and what not.
Go to system then app.
Go to market once you are running again and download Launcher Pro. You'll be able to install the newer versions from here on out.