I ended up having to completely default the phone, choosing "wipe data/factory reset" and "wipe cache partition". I had to do the same on my Nexus 7 tablet as well for CM10 nightly builds. You can try that (depending on what bootloader you're using, I used Clockwork Recovery. Question: Do you have the phone bootstrapped, and if so, which one are you using? I ended up using the "Droid X Recovery Bootstrap" by Clockworkmod, and the CM7 buildout for Droid X (the "camera/calander" button is non-functional, sadly)