MAKE SURE TO BACK UP BEFORE ATTEMPTING.
For Liberty 1.5 users uninstall it with root explorer in /system and then reboot. You should now be able to install the updated version

.
DO NOT use Titanium Backup to uninstall the app you will get an error and will not be able to install the update along with problems using sms.
I nandroid restored back to stock blur and was able to install the update with no issues so as far as I can tell it's a problem with Liberty 1.5 that can be worked around witht he above recommendation. I cannot speak for other custom roms.