Join Date:Joined: Sep 2011
Check to make sure the card is properly seated in the slot. If that's not it do some tests.
Sd cards do go bad sometimes. I would back up your sd card, double check its the G3 and not the SD card by putting it in another phone, and try another sd card(a friend's?). If your sd card is fine and another sd card doesn't work, your phone might be faulty. If its just your card and your card is ok, might be a weird compatibility issue.