Can't connect to wireless network

Hello,
I have a problem connecting to wireless internet on my laptop, running Firefox on XP. It worked fine until recently, when the network name changed from Virgin Broadband to Virgin. I didn't think the name would make a difference, and my housemate who's in charge of the internet says the key is the same - but if I try to connect to it, it either fails completely or tells me that I'm "not connected" or "disconnected". Either way I can't use the internet, but the strange thing is even if it says disconnected in the top corner of the wireless network list, the information below it will tell me that I am connected, and the button will say "disconnect from this network." Clicking on the network, it tells me how long I've been connected for - but it won't display any webpages. I've tried Winsock and resetting something in CMD, but to no avail, and I've messed around with the check boxes on Firefox that configure the proxy settings, as well as toggling on/off the "this key is provided automatically" setting in the network's properties. I now have no idea what else I can possibly do, any help would be massively appreciated.