Today my sisters netbook lost its wifi connection. I fixed it by going to the routers ip address. the name had changed to "wireless" and the wep keys were all set to 11111111111111111111111111111111. Did someone break in or could the router just have malfuctioned? Oh its a netgear router.
WEP is not that strong - I agree with Emerald you make sure remote administration is disabled. First thing you should do is change the router's name and password. But according to Emerald suggestion make sure to check your sister netbook if supports WAP2 before setting it.