unfortunately message has stoped

[Mukti1]

when i sent a message the pop-up always show and say unfortunately message has stoped, then until now I can't send message and acceptance message from another user. 
so may be anyone can fix this problem? 

[Uliwooly]

backup everything and repair your phone with SUS or PCC

Update Service (SUS)

PC Companion (PCC)

Bridge (for Mac)

Alternatives on How to backup Xperias

http://talk.sonymobile.com/thread/36355