If you stop it you break the gallery and will need to factory reset.
UPdate... Thought all was great by Saturday afternoon after aborting the update and restarting phone. Last night, I realized the photo gallery was locking up, notifications and ringtones are not found and this morning, the alarm would not sound. I guess the Media Database that it locked up during needs to finish it's converting or whatever it was doing.
I guess I need to hear someone point out, "you now need to do a factory reset," unless there's something else you know to help out.
Thank you,
Robb