Thank you, nunped. It must have taken a lot of patience on your part to help me, but you did the research, and got back to me in time to save my OS and all the data I've collected. I've become much wiser in the ways of teh internetz, and I've realized that there is a need to be proactive, rather than reactive, when it comes to viruses/malware. This site is a great resource for everyone, whether they believe their computer is infected or not, and I highly recommend it.
As it turned out, I remember downloading a "fish tank screen saver" some years ago, which never worked, and which I promptly forgot about. However it seems it had something to do with allowing a trojan horse infection to take root later. Thankfully it was not one of the most serious variety, such as a backdoor Trojan. I now know about the risks of "free" software. I was quite anxious at first to have my problem fixed, but the time spent lurking and reading the articles before posting really did pay off. I can now say

and I owe it all to nunped and the friendly staff here at malwareremoval.com.
Cowabunga!
ttfn