So I figured out why I couldn't install and/or run half the programs needed on my computer.
Freaking Avira was doing something in the background that halted almost all installer software or .exe files during execution, without causing them to terminate. So I'd, you know, try and execute something innocuous like WinAmp, get confused when nothing would happen, execute it again, come back later, do it again, and by the time I decided to check the Task Manager to see if there was some weird process tying things up, I'd have, like, seven instances of "winampinstaller" (or whatever; I'm not looking at it right now) 'running', and still no forward progress.
Tried to uninstall Avira with CCleaner. No dice. I actually physically had to go into the folder file, find the Setup executable, run that to remove all software, force my computer to shut down when the uninstaller hung (while 'stopping components'), restart the computer, rerun the Setup file so it could run again, and then restart again to complete the uninstall.
Apparently one of the components prior to the Setup hang was causing all the hanging. Go figure.
And good riddance.
Also my roommate moved out, and took his wireless with him, so I had to get my own package from Comcast, and now have that set up nicely.
I like how a summary of the morning's problems takes up, like, seven eighths of this post, and the explanation of the past week's absence takes one freaking line.