got my S3 about 3 weeks ago and love it, but about a week ago it started randomly erasing then reloading all of my emails- several times a day. I took it to get checked out and they checked the phone and did a complete reset...well, it happened again this morning!
Anyone ever hear of this happening?

Have you connected your phone to Samsung Kies and updated the phone's firmware? The update may resolve your problem, if not at least your firmware will be up to date.

Edit: Or update the phone from Menu > Settings > About Phone > Update (You will have to sign up to Samsung, this will also register your product with Samsung).

they did that yesterday at the sprint store, when they did a factory reset...no help.