At first I thought the hard disk was badly in need of a defrag (which it is), but then I noticed something peculiar. The only directories where I get CRC errors are directories with the word "Ruby" in them. So C:\ruby (where Ruby is actually installed), C:\ruby-1.8.1 (copy of the source) and C:\Downloads\ruby (various 3rd party packages) are affected and NOTHING ELSE.
I smell an overzealous Windows security fuckhead going nuts on my system. In the process, they fucked up the filesystem and now I'll probably have to have the damned machine reimaged. I've already confirmed that there was some "buggy" application monitoring "software" (i.e. spyware) that was on my system, and the help desk actually told me to uninstall it.
Well, at least I have this Sunblade to play on while I defrag the hard drive.