Be Wary of the Microsoft Update

It hit on July 9, 2008. Everything appeared to be normal as I turned on my computer and then accessed the Internet.
    Only, not so normal anymore.  After a long delay, my browser informed me that the web site I was attempting to access was taking too long to respond.
    Okay, I thought, I'll just click on the refresh button and try again. Alas, no web page loads.
    After a few more failed attempts, it's quite apparent that I wasn't going to visit that particular site at that time.
    Next site - Gather. I hadn't been here in a few days, so why not? Only problem, Gather seemed to be down as well.  I was unable to get any pages to load.
So, that made it much more likely that there was something wrong at my end, either with my Internet Service Provider or my computer. Attempting to access a few other web sites confirmed that. It was as though all web sites were down at the same time - extremely unlikely.
    After spending hours checking the settings on my computer and running a modem diagnostic, I began to wonder if the problem is with my Internet Service Provider instead.  Everything looked fine on my end and I had made no hardware or software changes since the night before, when I was able to access the Internet just fine.
Hmm.  Time to call my Internet Service Provider's technical support.  They could let me know if they were having a problem with their servers or assist me in further troubleshooting.  After about 1½ hours waiting on hold, I finally reach a representative, who turns out was unable to solve the problem either.
His suggestion to try accessing the Internet with the antivirus software shut down didn't work, but he did give me some ideas for further investigation.  By that time, however, it was getting late, so I just shut down the computer and went to bed.
    After days of fruitless attempts to rectify the problem, I was really starting to worry about having a hardware problem.  The modem seemed to be working just fine; it seemed like I was actually connecting to the Internet, just that there was nothing there.  But, could a problem with something else be interfering, like the CD / DVD drives or the CPU?

    Then, I remembered - on the morning of July 9, as my computer was shutting down, I had the message (paraphrasing), "Installing updates 1 of 1... Do not unplug or turn off your computer; it will turn off automatically."
    Oh, yeah, the automatic Microsoft updates.  Nah, Microsoft wouldn't have sent me something to disable some of my computer functionality, would they? But, I could think of nothing else to check.
Okay, in start → Control Panel → Add or Remove Programs, there is a checkbox for "Show updates", at the top of the window. Clicking on that checkbox causes the Microsoft Updates to be listed as well. They're listed under 'W' for "Windows".
    There it was: Security Update for Windows (KB951748) installed on July 9, 2008.  As it turns out, that was the culprit.