My girlfriend has an Apple I-pad. I would never buy such a product. She called me frantically one night that the I-pad would not connect to the internet despite it having full bars and all other computers in the house connected to the internet. Using Google to search for solutions, we came across the standard ones.... reset router, wifi, general settings, check MAC filtering, etc.... what we did- we used the USB cable to plug it into the modem and it connected immediately to the web, then we did a renew lease and it all worked. It was odd, I never saw anyone in e posts saying to just plug it into the modem... thought I'd say it worked. :)
An iPad cannot connect to the Internet by plugging it directly into a modem, it's not built that way.The only way to access the Internet is through wifi or a cellular data connection on 3/4g iPads. Your girlfriends iPad had to have been getting its Internet connection through wifi.
You should read this iPF thread.