Can you do me a log?
a) Create an empty file called “avast-debug” on your /sdcard root directory
b) REBOOT your phone
c) Now Avast generates a lot of log
d) Try to reconstruct your problem
e) After 10 minues, open Anti-Theft (NOT Mobile Security) and go to the feedback screen (About)
f) Check “Send system log”
g) Create a case there giving your email address and mention this conversation as well as a short description of the problem (maybe someone else will get the case)
h) Then remove the avast-debug file from the /sdcard root directory again
i) REBOOT your phone
j) Everything back to normal