There is a clue in this statement of yours:
However, it does work with Chromium
The problem is not due to Ubuntu 11.10 but the other web browser that you want to use to listen to this Internet radio station.
When I try to access the same station using Chromium iheartradio.com blocks me because I do not live in the USA.
When I try using Firefox the program freezes (window greys out) due to using all available system memory and some more of swap memory. (I used System Monitor to check this). Future updates of Firefox might rectify this.
I use Radio Tray. It is in the Ubuntu Software Centre. I works well with Unit. It puts an icon in the top panel (an app-indicator). You can use it change stations. Right now I am listening to Heartland Public Radio (playing Roger Miller - Dang me). I am listening to an American Internet Radio Station without needing a web browser. It must be better.
You need the Internet address of the station's radio stream. You create a new station using that address in the Radio Tray Preferences>Configure Radios option.
The address for Heartland Public Radio is http://hpr1.hpr.org. The address for Country108 is http://tuner.country108.com:80.
I give you these as an example of what to look for. I cannot give the address of the stream for KNRS because I cannot play that station. If you find out the internet address of the KNRS radio stream then you might be able to use Radio Tray to play it. Either that or use Chromium.