Infrastructure Software

out of 8 x 3 month old servers i have had 3 outages where network access is completely gone requiring a reboot.

setup
- sol 10 latest with patches
- hp BRCMbnx v4.6.2
- onboard broadcom 5709 in link based ipmp config ( is this supported? )

symptoms:
- switch says both links are up, link lights are flashing
- dladm show-dev link = up
- no ping or network access of any kind ,in or out
- physically pulling cable from bnx0 is not detected and link does not failover (ie dladm show-dev has link up when no cable inserted )
- reboot is the only way to resolve

Has anyone else seen any problems like this?
Any thoughts on how i can diagnose from the console?