Hello, I have an EXACT same problem with the user who posted in http://support.mozilla.org/en-US/questions/944098?esab=a&s=window+focus&r=0&as=s Just that his was firefox 17 and mine is firefox 20. The solutions posted to that thread was tried and it didn't solve my problem. I have also tried clicking the "reset firefox" option and after firefox resets, the problem still persists. I'm using the default firefox theme as well. OS: Win7x64 Ultimate Microsoft Updates: Up-to-date as at 23-Mar-2013 Here's a re-post of the problem description which he faced and what I faced as well: "Hello sir, I recently installed the firefox latest version (This is not an upgrade) on my new laptop running windows 7 premium, 64-bit. When I start the firefox, it's loosing the focus and I need to click somewhere in the firefox to make it focus. When I start the firefox in safemode, everything is working great. As understood from other questions, this seems to be the problems with the add-ons I installed. So, to investigate it, I disabled all the plugins and extensions, but no luck. Firefox is starting and but it's not focused. The issue is reported by my friend too, who is running the same configuration. This unfocused window is very annoying, please help us to resolve it. You help will be highly appreciated."