Hmm, no 3G or Wi-Fi I guess then, huh? From what I read on some other forums, and on the android market review page, you can hold down the home button to pull up recent apps (I heard that function should still work), if that works, hopefully either Settings, or Android Market are one of the listed apps. If you can access settings, you can either turn 3g back on that way, or possibly go to Manage Applications and clear the defaults for Launcher pro, then you can use whatever the default launcher is (Motoblur, right?). If you have the normal launcher, you can do everything from there. If you have android market, I think it will tell you that you need the network turned on, and (assuming it works the same as my Evo) will direct you to settings to turn it on. If you can turn it on, try installing it again through the Android Market.
I've heard if you install Launcher Pro through the market, it should work fine, and the error is only coming the the trial version downloaded from the website (I can't confirm that).
If neither or those are working, I also read that you can turn the phone on in Safe Mode and fix from there (I don't know how to do that, but I'm sure that should be easy to find online).