i havn't been able to connect to xbox live now for about 3 weeks

and its really bugging me.
My live was working and then all of sudden i couldn't connect, i havnt changed any settings or nothing. When i test my live connecton it said that my "Network:Failed" im using the wireless adapter....... but today i moved my xbox and my flat screen all into office and tried it with the cable - supplied with xbox and my live worked, but live doesnt seem work with wireless adapter

and the light on the wireless adapter is always red.
My internet service provider is sky and im using the newest router (black one) the make is DG934G.
Can anyone help me with this.....