Timer crashes my app

I just try to create a remote starter for my car with arduino,hc-06 and app inventor.
Because it will control the ignition and the self starter to avoid problem's (with the connection)
i thought i will sending something periodicly from app inventor to hc-06, after the bluetooth connection is alive. I think the simpliest way to do it just get a timer and sending a 1 byte decimal number.
The program is work, but after 2 minutes its just freeze and i have to restart.
If i dont use timer the program works fine, but without this is risky.