TestExecute process crashes while tests are running.

TestExecute process crashes while tests are running.
I have checked Event Viewer and this is the error message which appears every time TestExecute runs ("The TestComplete 12 Service service terminated unexpectedly. It has done this 16 time(s). ")
Also, I installed and configured DebugDiag app in order to capture the crash dump and no one of the processes we have configured was triggered.
The processes which were configured were:
- services.exe
- TestCompleteService12.exe
Can you tell what  I'm missing or give me some more information in order to determine why TestExecute process crashes.