Hong,
Since it is effecting multiple probes, Philip is right, make sure the OS is supported.
For troubleshooting, put url_response at log level 5 and log size 1000.
Deactivate all of the monitoring probes.
Set controller for log level 3 and log size 10000.
This will restart the robot.
Then activate url_response.
Check url_response.log & controller.log.