HP Vmware Advisory:

Transmit Queue Will Stop Responding on the Adapter on ProLiant DL585 Servers Running VMware ESX Server with One NC7170 Dual Port PCI-X 1000T Gigabit Server Adapter Installed in Slots 3 through 8 (100 MHz Slots), which results NIC stops communicating with the network.

Details are in URL for reference:

http://h20000.www2.hp.com/bizsupport/TechSupport/Document.jsp?lang=en&cc=us&objectID=c01086932&jumpid=reg_R1002_USEN

(The link is slightly slow & may take few seconds to open)