SBC Yahoo which I have. With that, you need to uninstall connection manager. You need to basically uninstall anything with a "broadjump" in its name. It sounds drastic but it worked. I used to get disconnected all the time and SBC would drop me hints as to what to do but couldn't tell me directly. I finally went here:
http://www.broadbandreports.com/forum/ilec,am
And they told me to uninstall Broadjump and use the existing connection manager that windows XP came with. I didn't know XP had one but it did and it works pretty good.
Maybe your girlfriend is having a similar problem. It sounds like it. See if you can use the built-in connection manager that XP has. I believe it is in Network Connections in your control Panel. You might want to do a search to find out if you can, though.