Wireless network connection stops communicating

Binary package hint: wireless-tools

I'm having problems with my wireless network connection. If I unplug the computer from the wired network, the wireless connection almost always seem to stop working, even though it's connected and have an IP adress. It doesn't help if I disconnect and reconnect to the wireless network or reboot the computer. If I try to open a webpage, the status field in the browser says "Resolving host" for 30 seconds, then displays an error page. The only thing that helps is if I deleted the stored wifi profile in the network settings and connect again. If I do this I have to re-enter the WEP key which is a hassle.

My computer is a Toshiba Satellite L450D with an Realtek 8172 wireless chip (using drivers for 8192SE though, since there's no native 8172 driver). Running Ubuntu 10.04 32bit.

I hope wireless-tools is the correct package name for this bug.