For those still with issues, after working with HP over the last few months, I now have what appears to be a stable platform.
I'm using the following combination which were released a few weeks ago:
Driver: VMW-ESX-5.5.0-elxnet-10.4.255.13-2555693.zip
Firmware: 10.2.477.23
Everything appears to be stable at the moment. I've introduced the same loads which previously caused the issues I mentioned previously.
Thanks,
Martyn