Try running Firefox in [[Safe Mode]]. (End the process in task manager before trying this.) If safe mode fixes the problem, then it's likely an add-on causing the problem. If it won't start in safe mode, try doing a clean install: # Hold down the '''Windows logo key''' and press '''R''' to bring up the ''Run'' dialog. # Type '''%PROGRAMFILES%''' (or '''%PROGRAMFILES(x86)%''' on 64-bit Windows''' and press OK. # Right click on the Mozilla Firefox folder and press '''Rename__. # Type in a new name, such as ''Old Firefox'' # Press ''Yes'' to confirm the name change # Install Firefox normally from [http://www.mozilla.com]