KCallahan: Agreed - File push and pull is fine - but no Sync.
BTW: Turning off the USB has stopped the hangs :) - albeit at the expense of USB based activeSync.
I'm thinking that the hanging may be a symptom of the low level communication with the HTC - maybe that the network activity on the HTC is craeting a virtual NIC that is then confusing my PC's network settings. This would cause a pause whilst the PC tries to communicate with Exchange / ISA via the wrong NIC. After the timeout the HTC NIC is ignored by windows and processing continues.
I'll let things run as they are for a while and see if I get any hangs. Sync is now via pull from the HTC over WiFi, which is not ideal due to the delays inherent in this approach, but it works withoug hanging - and that is a bonus
