Execution was triggered in Rational Quality Manager, but the tool exited before execution was complete.

Hi:
We have a test suite in RQM which takes long time to complete. When started with the RQMExecutionTool.jar from command line, the test cases are executing, but after about 2 hours, the tool through the error and exit. The remaining test cases will continue on RQM. Is there any setting cause this?
RQMExecutionTool version 6.0.6