I've been using Raspbmc for a while with an Asus USB-N10 wireless adapter plugged straight into the pi (no usb hub) for a while, straight out of the box, no problems. I also connect wirelessly to my router with all sorts of laptops, phones, wii, etc, again no problems.
Last week I decided to try a few new things with the pi. I'm using the latest wheezy release with default options (no overclocking or anything like that) and got the pi connected wirelessly after editing the interfaces file, no problem. Trouble is, my laptop loses internet connection when the pi is connected. It seems like a router reboot is the only way to get it working again. I can still SSH into the pi from the laptop though, even when the internet connection is lost, so it is obviously still connected to the router. Anyone have any bright ideas?