By default, Firefox shares one session across all browser windows that you open. To enable multiple sessions, you must create separate profiles that can be used by different sessions. For more information about setting profiles, see the Firefox help.
Before performing this procedure, close any open Firefox sessions.
In the Firefox - Choose User Profile window, select Create Profile.
In the Create Profile Wizard, create one profile for each Firefox session that you want to launch and then exit the Profile manager.
For detailed instructions for creating profiles, see the Firefox online Help.
After you complete creating the new profiles, create a shortcut to Firefox.exe on your desktop or Taskbar for each profile that you created.
Right-click the Firefox icon for each shortcut and select Properties.
In the Target field of the Properties window, specify the name of the profile to use when launching Firefox from that shortcut, for example, "F:\Program Files\Mozilla Firefox\firefox.exe" -P "ProfileA". Click OK.
Click Start > Control Panel > System.
In the Advanced tab of the System window, create a new environment variable with the variable name MOZ_NO_REMOTE and a variable value of 1.
Click each shortcut to open Firefox in separate sessions.