I ran across this issue while working with a customer to install vSphere 4.0 Update 2 on new Cisco UCS blades.  Our problem is that port groups on the dvSwitch cannot access VLANs. This prevents the ESXi hosts from accessing the iSCSI and NFS storage and networks for VMotion and the DMZ.

The issue only exists for vSphere 4.0 Update 2 when using Intel 10 GB network adapters.  A link to a more detailed description of the problem and essentially the same troubleshooting steps we tried can be found <a href="http://communities.vmware.com/thread/272441">here</a>.

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VMware has rated this a severity one issue but no fix is currently available. Possible workarounds are:
<ol>
	<li>Rebuild the hosts with ESXi 4.0 Update 1</li>
	<li>Upgrade the hosts to ESXi 4.1 (just released two days ago)</li>
	<li>On the ESXi hosts remove and re-add each 10g network adapter to the dvSwitch. This resolves the issue but the fix does not survive a host reboot</li>
</ol>
After reviewing the options the customer decided to stay with ESXi 4.0 Update 2. We removed and re-added the NICs to get things working. We left the support case open and will wait for VMware to release a patch.