Snort dies every night around 3:00 am. Why?

[andrew.macbeth]

I have Snort installed on a stand-alone network (no connectivity to the internet). All instances of Snort across the network die overnight, approx 3:00am. I don't see any output in log to indicate anything.  I suspect it's trying to perform an update and fails.

Does anyone have any ideas of where I can look?