Anything in the log file?That's a very good question Neil.
I found the log file and indeed the error in mine is associated with the radarbox24 feed.
I removed that one from my selected feeds and no longer get the same error.
There were a couple of:
but the planes are showing again despite these messages.System.Net.WebException: The underlying connection was closed: The connection was closed unexpectedly
I don't know how to set that ADSB Exchange feed path in the options.