I have a new computer. Sort of.
I ended up taking my computer to Best Buy. What they told me explains many happenings of late--yes, I had some malware on my computer, but the big problem was that my hard drive was starting to die. Fortunately I backed up the data a few days before I took the computer in.
They put in a new 1 TB hard drive for me, and despite the impending total collapse they were able to mirror the old drive onto the new one. All my programs, all my stuff, it's right where it was! Then they cleaned the malware off the new drive.
OK, so I'm $265 poorer, but now it's all like nothing ever happened. And I have lots more hard drive space to boot.