XP, like the previous incarnations, has various bits and pieces that send out via the modem that it is active and online. Various apps send out signals that they are present - and if there is some bot listening then down comes the bad stuff.
That box was likely left online for hours - plenty of time for something to get through the notoriously porous Win security, McAfee or not.
The only way to guarantee no bad stuff is to never connect a Win machine to the Internet, never insert disks, CDs or DVDs. Better yet, never turn it on - as MS advises.
The best way to fix this is to do a secure erase which will take some time, reinstall XP from the OEM disk, do not reinstall anything from any backup (all previous data is suspect), and get rid of the modem. All should be well after that. Go online and you may face the same situation again... soon.
Or you might just consider a totally different manufacture, computer, and OS...
Yikes!
I appreciate the info and suggestions
What is a “secure erase?
Get rid of the Modem? I don’t understand. How do I connect her then?
Linux Mint doesn't seem to have the easy capability...in fact no matter what I try on the internet it doesn't seem to acquire all of that good stuff.