Something must've gone wrong in the flashing process. You'll probably need to sbf (which isn't as scary as it sounds) but first pull the battery, hold down the power and x button and when the android pops up hit the search key. Using the volume keys to scroll, the camera key to select, and the power button to go back hit wipe data/factory reset and hit yes. Once that's done go back and hit reboot system.
If that doesn't work you'll need to do what's called sbf'ing. Now sbf means 'saved boot file'. You will need to get a program called winzip (you only need to use the free trial), rsd lite 4.8 or higher, and the Droid Pro SBF file, and the moto connect drivers. Now once you've downloaded the sbf file make sure you save it to somewhere memorable like downloads. Now plug your phone into the computer and open rsd lite. Before you do that power on you phone while holding the volume up button. It will boot into what's called the bootloader. Plug the use cable in and make sure the file is opened in rsd lite and the device is recognized. Then hit start. It should take about 5 minutes but don't hold me against that. Once its done unplug it, pull the battery and boot back into recovery (power and x) and do another factory reset as it will bootloop if you dont. It should boot up (initial boot will take longer
Than normal).
The commands for recovery, bootloader, etc. Are the ones used for the DROID 2, and global. I think its for the pro too. Sorry if they aren't but google is a useful tool. Ill try to do a little digging for the files. If you have any questions pm me and ill be happy to help.
Wow that took a long time to right up! :b
Sent from my now completely stock DROID2 Global
Was the ROM you tried to install the CM7 ROM for the Pro that is found in the Droid Pro Hacks portion of the forum? Since that is basically the only custom ROM available for the Droid Pro, you may want to make sure that you're not trying to flash a ROM designed for another phone...
Either way, you will probably have to sbf back to a Droid Pro OS in order to restore your Pro...