Share your experience!
Have you moved apps to the SD card? or games or widgets? because that's the reason you would get that icon.
Repair your phone with PCC
PC Companion (PCC)
Bridge (for Mac)
Alternatives on How to backup Xperias
http://talk.sonymobile.com/thread/36355
@datjcat
what if you boot on safe mode?
http://talk.sonymobile.com/t5/FAQ/How-to-boot-your-phone-into-safe-mode/m-p/348008#U348008
