Interesting. I have a different issue, but possibly related.
We use a Timy3 through a serial to USB adapter, which of course shows up as COM3 or COM4 to Split Second. A couple of races ago, SS hung because of port issues. Unplugging the USB adapter and plugging it back in cleared it. I didn't think much of it, but then it happened again at the next race. This "hanging" occurs after power-down for sync.
I mention it only because it's never happened before. Perhaps it's the result of a SS update?
-- Mark