Shoutbox

Do you actually have wireless internet, or do you have a wireless network, which is connected to the internet. Real wireless internet signals will be being beamed around your area, irrespective of whether you use it, or whether your PC is on. Transmission will be coming from you, though it shouldn't really have a different effect as what the rest of the signal did.

It might be a dodgy power supply, unless your sure that it's your wireless network (if you have one). Try testing the power supply on its own, with none of the rest of the PC plugged into it (use a power supply tester (borrow one)).