The autoruns program doesn't seem to indicate which programs were initiated through rundll32.exe. According to msconfig.exe, the only programs that are started that way are nvidia drivers. I tried disabling them, and rebooting, but it didn't resolve the issue. I started uninstalling and reinstalling other programs to see if I could narrow down which program might be causing it, but I figured if I was doing that, I might as well re-install Vista. So, another Vista re-install *sigh* problem solved.