Laptop cant detect OTHER wireless networks.

My brother have a laptop that cant connect or either detect other wireless networks available in the area of which my laptop CAN detect, while both of the laptop is in the same room. He needs to use the laptop beside the router we use(belkin) so that it can detect then connect to that specific wireless network only. His laptop runs in a windows 7; its a HP pavilion g6. My laptop works pretty well even in the living room which is far from the router and can detect the wireless network of the neighboring houses, so I figured out that its his laptop's problem. I have tried updating the 3 network adapters of his laptop, but still no use. I have also tried using windows or microsoft's guide to fix the problem of not detecting wireless networks. Well this problem started when we bought the router, then installed the cd of the router to his laptop. I already uninstalled it as well. I really dont know how to solve this challenge. Pls help me.. anyone who knows what to do with this. Thanks a lot in advance.