On opening Firefox after booting up my PC, the following message was displayed on the one and only tab: Well, this is embarrassing.Firefox is having trouble recovering your windows and tabs. This is usually caused by a recently opened web page. You can try: Removing one or more tabs that you think may be causing the problem Starting an entirely new browsing session There isn't the option to do either of the above-mentioned and the 'restore' button is greyed-out. The version of Firefox is 23.0.1 There are many important tabs that I need to retrieve. Any ideas? Thanks in advance.