For me. The Cappy started an issue with the mobile hotspot.

It would turn on, I'd connect my Xoom or laptop and after 10 sec it shut off. After a week of back and forth with att tech tier II we finally gave up and warranty replaced (my second, first one had the random shut off issue )

It also would not recoginze video and music files. And after hard reboot it be fine a for a few days then start up again.

I also had the MMS issue, and solved that by what other people said, taking out the parenthesis. I import my contacts from outlooks csv files and outlook would put the parenthesis in there.