Hi there all!
Had exactly the same problem not being able to access the admin panel (
http://192.162.0.1) of and AzureWave AW-NR580 as the router had thrown up the Username and Password box.
To solve the problem I held the RESET button in for around 10 seconds until all the lights went out and the router rebooted.
Once the router had rebooted, I went to the admin page I was not asked for the password and could continue to set up the router and now works GREAT!!
Hope this helps others!!