Problems with em0 driver after upgrade to r303832

[Pete French]

I upgraded my local machine to the above revision a few days ago. Since then I have seen the local em0 card locking up and getting he following
messages in dmesg

em0: Watchdog timeout -- resetting
em0: link state changed to DOWN
em0: link state changed to UP


I thought it was the physical card, but I have swapped this out
for a completely different one and the problems remain. Am am concerned
as we run a lot of em0 cards in production and started upgrading those too,
as I had not associated the problem with the software upgrade until just now.

Any siggestions ? Am reluctant to start rolling this back, and it is
only showing up on one machine for now - is anyone else seeing this ?

-pete.