Well, it looks like I was a little too careless on my Windows XP installed via Boot Camp and use via Parallels. I installed a program that turned out to be malware, thus causing the installation to be 0wned. I had AVG Free Edition loaded on it and it caught that this happened. I then uninstalled AVG and loaded up a copy of Blink Personal Edition, which is a bit more aware of that kind of stuff. It too started seeing malware-type stuff and isolating it.
Past experience suggests that once a system has been compromised in this way, your best bet is to ensure that the system is clean is a format and reinstall. Fortunately, there is no real data in this particular XP installation, so other than reinstalling Windows, all the security patches, and the applications, it’s a relatively straightforward process. Just time-consuming.