I sincerely hope that you or someone is able to find a fix for this gallery force closing.
According to droid-life, the only fixes so far are restoring a pre-nemo backup, or copying your SD card contents to your computer, then reformatting SD card, then copying back to SD card. I'm not sure how well the latter works, because I had a recent backup.
The problem appears to be located in a corrupted cache directory. After copying all SD contents to your computer delete the cache directory that is on your computer and then format SD and restore the files and directories from your computer to the formated SD. Reboot to recreate a clean cache directory on your SD card. This info is from the Moto Forums relating a fix for the Galery FC issue after the 2.1 OTA.