Anyway, while they haven't been able to help me with an admittedly obscure problem (*), they've certainly tried hard, and the problem is definitely not anything that the service organization is doing wrong -- it appears to be an engineering problem with the specific model of Dell that I purchased.
(*) I'm attempting to activate Intel Virtualization Technology in the BIOS in order to run software like KVM, Xen and VMWare. VMWare can run without it turned on, but runs much slower. The other two require it.