[Simon]

Okay so.... Did you try to uninstall AZ (uninstall everything even from cache) and re-install it again? I think you have a conflict somewere or something like that. Try unistalling it and install it back again but make sure you do this step.

First, shut down Azureus with File->Exit, then find your config files:
Windows: Click Start -> Run and enter %appdata%\Azureus\ Delete everything from there and after do an uninstall.

Let us know

Simon