A day after my last post, I lost the connection again. That, along
with so many other PC problems, prompted my to call in the Geek Squad.
The problem was that my computer was thoroughly infected. The only
solution was to wipe the hard drive & start all over. It's been
working perfectly since then.

HEADS UP: DO NOT download Xoftware or NoAdware. Instead of blocking
viruses, spyware, & popups, they open the system to let them all in
until the computer can't function.