Help with HP storage server and VMWare

We are in the process of deploying a small VMware visualization setup consisting of 2 ESXi hosts running on 2 HP DL380 Gen8 servers. We are using an HP Storageworks x1600 storage server running Windows Storage Server 2008 R2 with an added HP NC375T 4 port Gigabit NIC.

We're creating iSCSI drives on the storage server and passing them out over the 4 port nic, all the ports are teamed. In vCenter I can see all the iSCSI devices under the iSCSI software adapter details. The server sees them fine, when I go to add storage and point it to one of the iSCSI drives, it takes forever to create and format the filesystem. If the iSCSI drive is larger than 1TB it will flat out fail.

Once we finally get iSCSI storage added, if we attempt to migrate and existing VM that is hosted on internal storage on an ESXi host to the iSCSI drive on the storage server, it transfers so slow that it will eventually fail. If we pass an iSCSI drive out through the on board NICs on the storage server everything works perfectly. VMWare support has verified that we have everything configured correctly so we've narrowed it down to being an issue with the HP NC375T 4 port NIC. We updated the drivers and firmware to the latest version and still run into this issue. The issue is also not just isolated to iSCSI devices, we run into similar issues with attempting to use NFS shares.

Does anyone have any suggestions or experience with this particular NIC and ESXi 5.1? We're going to see if we can get HP support in today to give us some help as VMWare says it's an issue with the storage server.