User Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:18.0) Gecko/20100101 Firefox/18.0 Build ID: 20130116073211 Steps to reproduce: I attempted to open a window using Control+n. I also attempted this manually, by using File > New Window. I also tried to open links by shift+click or right click and "open link in new window". Actual results: The window did not open after trying any of these methods. This entry was generated in the console: Timestamp: 1/28/2013 10:10:55 PM Error: this.docShell is null Source File: chrome://global/content/bindings/browser.xml Line: 323 This exact error (minus the timestamp of course) occurs regardless of how I attempt to open a new window. Expected results: A new window should have opened.
Have you tried in firefox safe mode? Its most likely caused by a broken extension.  https://support.mozilla.org/en-US/kb/Safe+Mode
Restarting firefox fixed it. At the time, the only plugin I had enabled was AdBlock. I will close the ticket.