So I zap adware like mad. Then after Adaware closes: NO NETWORK CONNECTIVITY! System restore can't see far back enough to restore the network, either. It's 10:00 pm, I call it a night and take her computer home with me. Finally found the solution last night:
Problem: The computer has lost network connectivity.
Symptom: When entering ipconfig /renew at the command prompt, one receives the message "An operation was attempted on something that is not a socket"
Diagnosis: Adware or another program has inserted another layer between the user and the TCP/IP Winsock system. If the installation or removal of the software is bug-prone, network connectivity can be lost.
Solution: Download WinsockXPFix.exe from the internet on another machine and run it on the broken machine, after backing up said machine's registry as a precaution. Network connectivity will be restored.
Both Comcast and Dell technical support didn't realize the problem after they were told about the wierd ipconfig error message. I'm sending them e-mails informing them of the problem and the solution.
As for little sister? She's going to be running Adaware very often from now on. And maybe Opera instead of Internet Explorer, too.