S-function cause overflow on memory and the embedded program crash

Hi,

I'm working in a embedded program in simulink and Tiva C launchpad. I'm trying to do an UAV controller with IMU, GPS and Xbee, so I made a s-function block for each sensor. All works fine when I tested separately, but when I tried to use the 3 s-functions in the same model, the program works fine for some time (some cases 5 sec other 2 minutes), but finally the program crash.

I suppose that the cause of the crashing is because the memory overflows or some problem with the memory, because I can't understand how a program can run some time and in some moment get crashed.

I'm totally lost about how to continue checking for solutions.

The code is very large to copy here, but if it's neccesary I can upload it.

Thanks Alberto