I don't know. Netzero worked very hard to create a software connection manager that required it to be running at all times. You couldn't even authenticate without it.
Yahoo may have done something similar, but I am not sure.
Only the original poster can tell us what kind of software is installed on the systems. Banners and such would be a good indication of software connectivitiy.
"Imagination is the only weapon in the war against reality." -Jules de Gautier
Not easily intimidated by common sense...
The Official Playground Machine Empath and Geek Gawd