Watchdog timeout

Hi all

I installed Motion to BBB. And I was streaming video webcamera.
OS is Ubuntu 14.04.

When 320x240 settings of Motion, streaming has been successfully.
However, it failed when the 640x480 settings of Motion.

Then syslog
motion: [1] Resizing pre_capture buffer to 1 items
motion: [0] httpd Closing
motion: [0] httpd thread exit
motion: [0] Thread 1 - Watchdog timeout, trying to do a graceful restart
motion: [0] Thread 1 - Watchdog timeout, did NOT restart graceful, killing it!

I have also Beagleboard-xM, and I can stream 640x480 pixels on Beagleboard-xM.

I thought that the cause of the failure depend the ability of the BBB.
However, when tested using the mjpg_streamer, at 640x480 pixels, I was able to streaming.

What is cause of Whatchdog timeout?

Having the same issue on my BBB (element14)