After disabling the internal SD card slot, the installation finished without a hitch.
Trying to install Hyper-V (bare metal hypervisor, not a role) on T420 with PERC H710, getting an error message: "We couldn't create a new partition or locate an existing one. For more information, see the Setup log files." (Don't even have a clue where to look for "Setup log files" - don't think the installer has a place to write them to.) What am I doing wrong here? The server came with a pre-partitioned RAID1 mirror on H710 (the rest of the drives - yet unconfigured); dual SD cards with the VMWare hypervisor (to be erased or left alone). Thanks in advance for any ideas.
Installing Hyper-V 2012 on T420: "we couldn't create a new partition or locate 
an existing one"