Here is how to have several Firefox windows open – each with different proxy settings.

1. Close any open Firefox windows. Use ‘Run’ command from windows start menu, type in the box: ‘firefox -P’ and click ‘Ok’ button
   
2. What you see is a Firefox profile manager. Now you can create as many profiles as you need. In this example we created one additional profile called ‘NewProfile’
   
3. To run different profiles at the same time you have to start firefox using this command: ‘firefox -P profilename -no-remote’. Now you can set different proxies for each profile (Firefox proxy settings) and run them simultaneously in separate windows.