Jan 2014 = TRY REBOOTING PHONE MULTIPLE TIMES.. TRY RE-INSERTING SD CARD . WORKED FOR ME..
had corrupted sd card, phone says to try re format ,warning that it would erase sd card..! .
I did not do this.. *****
I just re-booted phone several times, re-inserted sd card... and sd card was accessed ok with no errors. !.. Lucky , I guess.
My SD and int storage was maxed at the time , had issues taking pics, videos.
I have since transferred photos from sd to computer, int storage to sd card and to computer.. later to thumb drives.
Int storage to sd card using move command takes awhile , not sure half hour or more.