It used an internal wireless adapter (we have a wireless router that isn't too far from it), and worked perfectly for a long time, but then this became unreliable so I bought a Belkin 802.11g wireless adapter which then worked perfectly itself for another long time. In fact, after that, both of them worked fine. Recently it began to be temperamental, and now it's been completely unable to connect to the internet for a few days.
It can't be the router's fault because every other computer connects to it fine, and it can't be distance from the router because it won't connect when it's right next to the router either.
I've tried everything I can think of but nothing's worked: if anyone has any suggestions at all for me please do say so.