My understanding is that on the Droid 3, you cannot move apps to the ext-SD card, but you can move them to the int-SD (Media area).
That being said, I, and several others, have reported that there seems to be a problems with moving apps to the Media Area of the int-SD card. This problem shows up in several ways, you wake your phone up or power/down power up ant the apps are messed up. When you go to Menu/Settings/Applications/Manage Applications/ the app name was been replaced by a cryptic name such as com.appname...... If you try to run the app, the message 'App not found' pops up.
This problem was been around for several months. I first encountered it on my OG Droid and I encountered it on my Droid 3. I no longer move apps from 'phone storage' to 'media area.'
Good Luck,
Bob