Hello,
That was indeed what I was saying, that with average network loads of at approximately 1Gbps this issue would happen, and with startling frequency - approximately once every 15 minutes.
I have performed the iperf test and was unable to replicate - I am currently attempting to create the conditions under which this fault occurred using standard test software. This happened in an environment that had many, many multicast packets, so it is possible there is an issue in there. I maintain that the driver should never fail to deliver a timestamp while still being responsive to user input, but it is clear that the conditions under which this occurred are highly specific - please stand by while I attempt to create a minimum set of conditions under which this occurs.