The Zoo over Ambuscade Street

Yeah, I second the Thou Shalt Not Multitask. Also, Applications -> Utilities -> Activity Monitor will let her take a look at what's sucking up resources. If she's using Firefox, it will occasionally develop a nasty memory leak and start bogging down the entire system, and if she's got any of the Microsoft Office apps for Mac open, those are likely candidates as well. Also, reboot, if she hasn't already.

(Not a Mac expert, I just live with one.)