Still no resolution with this from ImmersionRC. They posted a short time ago that they think they've figured out the problem but it's been weeks and a solution still hasn't been released. The problem seems to be that the USB drivers will initially work and allow the ImmersionRC software to link to the Tx or Rx but the connection will fail if you try to do anything other than view the first page. Some people report no problems while others are having the same problem I'm having.
I've considered removing the other multi-rotor related software bundles (Mikrokopter, DJI, 3DR, Hoverfly, Eagletree, Castle) from the computer so as to give the ImmersionRC drivers less clutter to interfere with them but that shouldn't be necessary as the other drivers all seem to work fine with each other being there. At no time did I try to run the IRC software while another package was running and have even tried running the IRC Tools software from a fresh reboot but nothing.
Rather than operate my EZUHF system with old firmware that can't be updated or configured properly I've decided to replace everything with a Dragonlink UHF system and I'm happy to report that that went exactly as described in the manual and it is ready for its first flight once the weather breaks.