It happened to a guy in Russia, but he doesn't know either.
http://www.cyberforum.ru/viruses/thread1264398.html
Should be possible to check the Task Manager during an "appearance" and find out what's tossing this up. I suspect some kind of adware for a "fix your computer" service. Any number of widgets out there that promise to keep your drivers up to date, or registry "clean."
Sometimes you can find the problem just by prowling "Programs and Features" and looking for "mystery installations."
