Timer and UDP BytesAvailableFcn property stops working for some time: what to do?

I use MATLAB for gathering experimental data. During the script execution timer and udp objects are created (TimerFcn property in timer object is set to ctrl.registration.loop() function, BytesAvailableFcn function is set to ctrl.stimulation.whenReceived(), all methods are protected). After that script does nothing.

When gathering and processing experimental data these two methods are called approptiately and work stable, without any errors. However after 20-30 minutes of such work something happens and these methods don't execute (timer ceases to launch ctrl.registration.loop() every 3 minutes, udp object doesn't launch ctrl.stimulation.whenReceived() despite of constant receiving UDP packages, BytesAvailable property of UDP object is always 0). MATLAB doesn't show an error and System Monitor points a drop in processor usage and memory engaged. It seems like execution of timer and udp "hangs".

The situation lasts for 5-10 minutes. After that the problem solves without any influences from experimenter and without any visible reasons: ctrl.registration.loop() continues to execute every 3 minutes, MATLAB receives all UDP packages it didn't receive for the "hang" and starts to process. Gathering the data "switches" to its ordinary mode, no errors and data loss happens.

So, could you tell me, please, what the reason of this "hang" and how it can be corrected.

I use MATLAB R2011b in P4, 640 Mb operative memory, > 10 Gb free disk space.