Another thread also suggested the work-around of using File > Configure Other, which does work when you encounter this error. You can then manually access the desired router. That does not resolve the issue, though.
I also thought that the error might be related to my use of Apple's Wireless Distribution System (WDS) to connect my Airport Extreme with a remote Airport Express. However, this problem is obviously not an Apple issue but a basic Microsoft one: corrupt TCP/IP settings. I hope that this helps and saves others some time.
Destin, FL, USA