Open multiple profile Firefox at once

Case 1:

Step 1: Open System Properties, choose tab Advanced, click to Environment Variables button. In System Variables section, click New. Type this information to each textbox.

Variable name: MOZ_NO_REMOTE

Variable value: 1

Press OK to close all windows.

Step 2: Open Firefox icon's properties. Add extension -p to command line. Press OK.

Now, when you open Firefox by click to this icon, you can choose profile of Firefox.

Case 2:

Open notepad (or other)
Enter:

------------------Content below---------------------------

@echo off
set MOZ_NO_REMOTE=1
start "" "C:\Program Files\Mozilla Firefox\firefox.exe" -p
set MOZ_NO_REMOTE=0

-----------------------------------------------------------

Save as (whatever).bat
That's it.

You can also do this for Thunderbird. :)