Ok, here's the situation.

I live with 3 friends, and we often sit in the living room with laptops out. There's a WiFi router in the kitchen, and we have quite a stable connection.

The issue, however, is this: sometimes, all of a sudden one of my friends loses internet connection. Even disconnecting/reconnecting to the WiFi network does not help. When we restart the router, though, it works like a charm again.

The odd thing is, it happens just for this one Windows 7 laptop. We've switched routers (for a different reason) in the mean time, but the issue remained. This makes me suspect the laptop even more.

I realise I've given little details, but I don't really know what to try/do. Any suggestions what it might be?