When I boot ESX 4 with the latest up on our UCS B class blades I get a:
"Failed to load iommu driver" and when it finally finishes booting on the first screen I have message in red:
cpu1 :4106)Mod: 2077: Initialization for vtd failed with -1"
I already have Intel Virtualization Technology enabled on all of them. This message wasn't showing last week but it started showing today.