I'm having the same problem after running a few months with a random reboot every so often, which I've found with this phone as well as my D1.
Running Liberty v1.5 w/Honeycomb theme. I've already tried reboots, battery pulls, SD card pulls, and full battery drain but no luck. Even tried wiping everything+cache on the phone several times and installing Liberty v1.5 but same trouble. I've since wiped everything + cache multiple times and re-freshly installed Liberty v1.5/Honeycomb multiple times, but my Droid 2 is still acting like it's possessed.
I haven't yet tried installing stock or a different ROM yet. Interested to see if anyone has had the same issues and a fix.