Solved; please do not ask how, as it is quite beyond my comprehension:

Yesterday morning, when I found that SuperAntiSpyware would not update, and not yet knowing that other programs were also not working, I submitted a support ticket. This morning, I found a reply to that ticket, telling me how to access it, so I clicked on the link.

I was taken directly to the ticket, which was not at all what the e-mail instructions told me, but found that I could not post a reply in Firefox. I then clicked on the Firefox extension that allows Internet Explorer to run inside FF, but the result was an error page that the page could not be displayed.

I next started IE and tried to access the Super ticket; the result was the same error page. On that page was a button offering to try to resolve communications problems, so I clicked on that button.

Clicking on the button brought up QwikCare, the Qwest software program that analyzes and tries to fix DSL problems. QwikCare found that the modem settings for IE, whatever those are, were incorrect, and started trying to fix them. After a while, QwikCare stopped responding, so I closed.

I then found that I could reply to the Super ticket in IE (but still not in Firefox,) that the Windows 7 Help system is now accessing the Internet, that clicking on the Super icon and selecting "Check for Updates" works, and, finally, that AllMyBooks now accesses the on-line databases it uses to help index books one owns.

As somewhat of an aside, I have had QwikCare, which always monitors, appear on screen three or four times recently and fix problems. Why this frequent need to run QwikCare's analyses is also unknown to me. Over the past few years of using DSL, I've only had it appear quite infrequently. In addition, I ran it yesterday, wondering if something else had gone wrong, but QwikCare reported no problems.

Do I know why something else, in this case apparently directly related to IE, happened during the night of Sunday/Monday? Of course not. Do I know why so many other DSL problems recently? Of course not.

Am I going to contact Qwest customer support? Only if absolutely necessary, as it tends to be useless. Example: A year or more ago, DSL stopped working, and Qwest support told me that there were no problems with their system. The "no problems" were reported, a day or two later, in the local newspaper as having been a major DSL outage.