Recently there are couple of issues I had faced on the latest DL 585 G7 server which installed with ESX 4.0 Update 2. The common problem reported by couple of users are same which could potentially caused all the network traffic dead off for the entire ESX host. The even worst case could be happen and cause Purple screen to the ESX host. The current solution is to either update the NICs driver with the latest version, but I will suggest to disable all on board NIC and replace with either Broadcom and Intel Gigabits adaptor. This will isolate unnecessary issues which I had not seen in others servers brand.

Please refer to the VMware Forum Here for the confirmation on bugs with multiple users who experience the same issues as I did.