So as of about 2/3 weeks ago my firefox hasn't been itself for some reason unknown to me. Every time i load it up it starts as a black tab then loads to google. This black tab problem happens on 90% of websites i open, before it loads the tab is black. Another problem I am having is with pop ups. I use a website and to download thing its a pop up and it works fine on IE and Chrome but with firefox it freezez and then Firefox crashes. I'm also getting a lot of what i would call lag again only with Firefox as it's taking longer than it used to, to do anything.
I have tried resetting it, I have tried uninstalling completely and reinstalling but still no difference. Btw I'm on Windows 8 if that helps anything.
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.
On Mac you can open Firefox 4.0+ in Safe Mode by holding the option key while starting Firefox.
On Linux you can open Firefox 4.0+ in Safe Mode by quitting Firefox and then going to your Terminal and running: firefox -safe-mode (you may need to specify the Firefox installation path e.g. /usr/lib/firefox)
Or open the Help menu and click on the Restart with Add-ons Disabled... menu item while Firefox is running.
Once you get the pop-up, just select "'Start in Safe Mode"