After working with my Sony Xperia for several weeks, all of a sudden it failed to connect to my computers. This is a very simple fix.
- Disconnect the Sony Xperia S from the PC.
- Turn off USB debugging if it’s enabled:
Menu > Settings > Applications > Development > USB debugging
- Clear data for the MTPapp in the phone.
Menu > Settings > Applications > Manage applications > All > Mtpapp