Since Firefox 20, Firefox keeps unresponsive after using Hibernation mode (not Stand-By, Not Power Save) on 2 of my Windows 7 x64 systems (most recent Java, Flash & Operating System updates). Even in Safe Mode. The problem is, that none of the elements respond to clicks ( site itself, tabs, menu-bar, close, toolbars,status bar, minimize maximize etc.) or scrolling nor does firefox react after killing the plugin container or flash player via the task manager. Seldom (1 in about 20 times) a "script unresponsive" dialog showed up without effect when selecting "Stop Script". The problem seems independent from the site opened (be it Google, Facebook, plain HTML sites without any active content) and also independend from the number of sites opened since it shows the behaviour even if only one page is opened. The one strange thing is that one is able to save all currently opened tabs by using CTRL+SHIFT+D. "The Save All Bookmarks-dialog" immediately shows up and has absolutely no responsiveness issues. The problem persists until you force close it via the task manager and restart it. Things i tried: - Wait for 20 Minutes - Power Save Mode (Stand-by that reacts on mouse movements) -> Problem not occuring - Firefox Safe-Mode -> No positive effect - Reinstall Firefox -> No effect - Reinstall Flash & Java (x64 Versions) - Machines are: Lenovo U410 (Core i5, 8GB, SSD, Firefox on HDD) & Custom System (Core 2 Duo E8500, 4GB RAM, 256GB Samsung SSD 830 (Firefox on SSD), 2x2TB Seagate Barracuda Green)