Hello artiom, '''Try Firefox Safe Mode''' to see if the problem goes away. Safe Mode is a troubleshooting mode, which disables most add-ons. ''(If you're not using it, switch to the Default theme.)'' * On Windows you can open Firefox 4.0+ in Safe Mode by holding the '''Shift''' key when you open the Firefox desktop or Start menu shortcut. * Or open the Help menu and click on the '''Restart with Add-ons Disabled...''' menu item while Firefox is running. [[Image:FirefoxSafeMode|width=520]] ''Once you get the pop-up, just select "'Start in Safe Mode"'' [[Image:Safe Mode Fx 15 - Win]] '''''If the issue is not present in Firefox Safe Mode''''', your problem is probably caused by an extension, and you need to figure out which one. Please follow the [[Troubleshooting extensions and themes]] article for that. ''To exit the Firefox Safe Mode, just close Firefox and wait a few seconds before opening Firefox for normal use again.'' ''When you figure out what's causing your issues, please let us know. It might help other users who have the same problem.'' Thank you.