No connection via WLAN
I am using a Belkin WiFi stick on my PC. I can connect and have internet but after some time, the internet connection is lost. The stick is still connected to the AP (I can see it on the AP and in my local connections overview) but I cannot use the internet anymore. If I start a ping after I got a connection it will remain until shutdown. I am using F18 but had the same problem on F17 and a colleague of mine has also exactly the same problem with Raspian. He also uses a different AP then me so that's why I think it is a more general problem.
Thanks for any help,