I'm looking into compatibility between Map Rank and Tab extensions so here is a new thread for it.
Map Rank opens up a popup window. By default this should open in a new window but some extensions by default
open popups in a new tab instead which will give you a blank window called "Untitled" and prevent Map Rank from working.If you have tried Map Rank and get nothing but a blank window called "Untitled"
1. If you have Colorful Tabs, then disable it. Colorful Tabs has no settings to allow default behaviour for popups.
2. If you have Tab Mix Plus:
Go to the Firefox Menu and go to Tools->Tab Mix Plus Options
Then Click Apply, close the options window and run Map Rank again.
If there are any other Tab extensions that prevent popups from opening in a new window please let me know.