Sounds like something in the router or PC is keeping her out. Does she have any security enabled on the router??? Best thing to do is disable all security and MAC address filtering inside the router. The easiest way to make sure everything is disabled is to reset the router. You can either do this from IE or with the reset switch on the router itself. If she is on DSL/PPoE you really don't want to reset the router unless you know the DSL setup information and the router is handling the PPoE. Is the hardwired computer handling the PPoE or is the router. I curently have my router handling PPoE and DCHP, but it is also possible that the PC is doing the PPoE/DHCP.
Here is how I have my DSL setup.
Speedsteam 5100B modem(setup as a dummy modem)>Linksys WRT54G Router handling PPoE and DHCP>Wireless laptop and hardwired PC.
All DSL settings are done inside the router and NOT the PC. If she is using the PC to handle the PPoE, it is all different.
I would suggest getting into the router through the wired PC. Go to Internet Explorer and type in "
http://192.168.1.1" and the hit the "Enter" key. This should get you the login screen to the router. The default user is blank with a password of "admin".
Once inside the router look at the internet and wireless settings. It should give you a clue on whats up.