After running automation using Silk 2009 R2 for almost 2 to 3 hours I suddenly see no script being executed and Silk status just shows it is waiting for control's property value even though the control and windows are available.
When performed <Shift><Shift> and aborted the test I get below error,

*** Error: Bad channel to agent call.

The above error is very consistent and occurs when running test for long period of time. I have seen this in Silk 2006 R2 also.

Any suggestion or idea why this problem occurs.

I followed up with local IT guys to find if there was any intermittent network disconnect between Silk host node and remote node where script is being executed, they said no.