What ends up happening is that some Windows component asks for permission to modify system files, and if you say "no" it pops up again immediately. The theory here (I guess) is that most people will just hit "allow" without questioning WTF is going on because this kind of thing pops up a lot when you have UAC enabled.
But I didn't; it came up apropos of nothing, and so I investigated before hitting "allow". Turned out there was an application running which was a long string of numbers--about 32 digits or so--and that is bad juju, so I ended that task instead of letting it run.
One of the ads at Mangareader.net is responsible.
This annoyance also crams an invocation of the file into your registry--hkey_current_user\software\mic
What I didn't twig to in time was a trojan that made it look as if Windows Defender had shut off...and by the time I realized that something was wrong, my system was infected with it. This was a pretty sophisticated one; I mean the thing that popped up looked just like it came from Microsoft.
EDIT: This trojan did not come from Mangareader; it came from another site. /EDIT
Problem: it inserted itself into the registry such that whenever you tried to run any program, it would run the malware too...and when I removed that nonsense I accidentally bolluxed my machine's ability to run any program. *sigh* I could run the mail program, I could run most of the applets in Control Panel, but I couldn't run Firefox or regedit or most anything else.
I spent a fruitless hour searching for the correct registry key (in my administrator account) in order to correct it; finally I figured out that I could run Firefox by double-clicking on an HTML file (my bookmark file) because Firefox is associated with that file type: double-click on an HTML file and Windows auto-invokes Firefox to display it.
Then I was able to go back to my regular account, run Firefox, download a registry fix, and--again--because I had the registry file, regedit could be invoked by double-clicking the .REG file.
Bip bap boom, computer worked again.
It really is getting to the point that I would like to make the penalty for generating malware a hanging offense--preferably by piercing the malware writers' nutsacks with hooks and hanging them that way. (Or "labia" if the programmers are female.)
...and again I recall that I'm a 95th percentile computer user. What do people do when they can't hack around like I can? (And I'm not even really that good!)
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Cue the usual comments, Mac/linux/blah-blah-blah etcetera. What I need is to upgrade this thing to Windows 7, which I'll do sometime after I do all the other shit that's on my plate....
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So, to make me feel better, here's some humor from the Sketchbook manga: