Did she/they really do WEP encryption (which, well, sucks), or are you just using that as a catch-all term for encryption?
If it really is WEP, I'll hazard a guess that the problematic laptop's wireless card (or, rather, its drivers) simply don't behave well with WEP.
Try turning the encryption up to something a little more, ah, modern (WPA or WPA2), reconnect everything to the network, and try again.
Also, make sure that you laptop's wireless drivers are at the latest-available version.
(BTW: "Atheros" is rather vague - model# would clarify things a lot, as would OS on the laptop.