Thank you very much this solved our problem here on our HP Proliant dl380p Gen8.
Updating wasn't working at first:
FROM: VMware-ESXi-5.5.0-1331820-HP-5.71.3-Sep2013.iso (ESXI 5.5 Build 1331820)
TO: VMware-ESXi-5.5.0-Update1-1746018-HP-5.74.27-Jun2014.iso (ESXI 5.5U1 Build 1746018)
Manually updating the Broadcom drivers corrected the issue using the 5.5U1 update ISO on a USB key !
Thanks