The more I looked into it, the more I felt that it was a networking issue. Ip addresses that I couldn't ping, DVR's with the wrong name in Tivo desktop, only one DVR seen in Tivo Desktop, etc., etc. I started at the router, then went through every device on the network and rebooted each one. Voila! All is working correctly now. Amazing what a simple reboot can do at the right (wrong) time. Thanks for all the suggestions!