DarWin-OP is shutting down from even the slightest impact, like sitting down in the interactive mode section and walking. If I lessen the impact of sitting down by grabbing its handle it continues through the interactive mode without shutting down. If I hold it in mid air using its handle and give it a command to walk it works fine but as soon as I put it on the floor it takes one step and shuts down. I even tried gently tapping his chest when DarWin-OP is in demonstration ready position and that also causes an immediate shutdown. The shutdown is not due to loss of power as I can see the green LED blinking the same way as it would do in a proper system shutdown. This very abnormal as DarWin-OP used to walk and go through the entire interactive mode without any interruptions or shut downs. Please let me know what should be done to diagnose and fix the problem.