as of late my laptop has lost its ability to be useful!

in our house we are running a belkin wireless router(running direct from the broadband modem), a built in wireless receiver(in my sis' laptop) and i'm running a 54mps belkin USB reader thing.

previously it was working fine, but it progressively lost its ability to connect...however the main computer, and my sisters laptop still connect fine

i've bought a new wireless adapter, and since re encrypted the network to make sure that was fine.

the reader is accepting there is a network there, and the status monitor is saying its running 54mps/good strength. however when anything internet related is opened it says there is no connection?

when internet explorer opens, in the bottom left bit of the task bar, it says detecting proxy settings, and then it comes up with the screen saying this page cannot be displayed etc!

this is beginning to get annoying as i need the laptop to get my uni work sorted on!

does anyone have any idea what this is, and more to the point how do i resolve this issue??

(might also be noted that the 4 point usb hub on my laptop 3 of the hubs feel loose so to speak- but this one is running through what i feel is the best one)