i do have the exact same problem, but this seems related to the MMS function. App works fine unless you are sending/receiving a MMS. I posted this some time ago: http://miuiandroid.com/community/threads/2-3-30-mms-problem-sgs2.16035/
I do have the same problem in 2.4.6, tried reflashing, and of course clearing dalvik cache and regular cache. Still same problem.
As a workaround ive installed GoSMS app instead now which deals with MMS fine.