Having this same issue. All my VM's in vSphere 4.1 (ESXi 4.1) that have iSCSI RDM's mapped lock up on boot and I have to reboot the ESX server. If I remove the RDM, the VM will startup but as soon as I attach the RDM LUN, it locks up. Any ideas? This just all of a sudden started happening last night. Both my Open-E servers were running for 540+ days without any issues..