FIREFOX OPEN ONLY HALF ON MY LAPTOP SCREEN REST IS BLANKC

Question

firefox with yahoo home page opens only half way on the laptop screen. That is first half of the laptop screen is blank while the yahoo window will start on 2nd half horizontally. all web sites will also be displayed on half of the screen (2nd half). in case of other browsers such as internet explorer or chrome all web windows will display fully on the screen.I tried to uninstall and reinstall the Firefox but the problem has persisted. so much so i have stopped using FIREFOX FOR BROWSING. KINDLY HELP IN TRACING THE FAULT.

Answer 1

-> Tap ALT key or press F10 to show the Menu Bar
-> go to Help Menu -> select "Restart with Add-ons Disabled"
Firefox will close then it will open up with just basic Firefox. Now do this:
-> Update ALL your Firefox Plug-ins https://www.mozilla.com/en-US/plugincheck/
-> go to View Menu -> Zoom -> click "Reset"
-> go to View Menu -> Page Style -> select "Basic Page Style"
-> go to View Menu -> Toolbars -> unselect All Unwanted toolbars
-> go Tools Menu -> Clear Recent History -> ''Time range to clear: '''select EVERYTHING''''' -> click Details (small arrow) button -> place Checkmarks on '''Cookies & Cache''' -> click "Clear Now"
-> go to Tools Menu -> Options -> General -> ''When Firefox starts : '''select "Show My Home Page"''''' -> Type the address of the website which you want to be your HomePage e.g. http://www.google.com
-> go to Tools Menu -> Options -> Content -> place Checkmarks on:
1) Block Pop-up windows 2) Load images automatically 3) Enable JavaScript
-> go to Tools Menu -> Options -> Privacy -> History section -> '''Firefox will: select "Use custom settings for history"''' -> REMOVE Checkmark from "'''Permanent Private Browsing mode'''" -> place CHECKMARKS on:
1) Remember my Browsing History 2) Remember Download History 3) Remember Search History 4) Accept Cookies from sites -> select "Exceptions..." button -> Click "Remove All Sites" at the bottom of "Exception - Cookies" window
4a) Accept Third-party Cookies -> under "Keep Until" select "They Expire"
-> REMOVE CHECKMARK from CLEAR HISTORY WHEN FIREFOX CLOSES
-> go to Tools Menu -> Options -> Security -> place Checkmarks on:
1) Warn me when sites try to install add-ons 2) Block reported attack sites 3) Block reported web forgeries 4) Remember Passwords for sites
-> Click OK on Options window
-> click the Favicon (small drop down menu icon) on Firefox SearchBar (its position is on the Right side of the Address Bar) -> click "Manage Search Engines" -> select all Unwanted Search Engines and click Remove -> click OK
-> go to Tools Menu -> Add-ons -> Extensions section -> REMOVE All Unwanted/Suspicious Extensions (Add-ons) -> Restart Firefox
You can enable your Known & Trustworthy Add-ons later. Check and tell if its working.