run in safe mode and spend 3 hours doing malware/virus scans.
i'd set up a both malware and virus scans in task manager as a weekly thing if she won't run them on her own. you could also have them set to start up before their scheduled update.
this will slow down the computer if it's old, but she probably won't know how to close the programs.
Mabinogi - Ruairi ch5 - Spliff