WOW! never heard of this....it she absolutely certain she didn't hit some key or key combination which restored the computer to it's original settings? I have never heard of a virus or trojan that would do this.
Give us full info on the computer...OS, anti-virus program, internet connection...everything you think we would need...maybe even what you don't think we would need.
Is she absolutely certain she didn't do a Repair of the os?