This issue can be caused by an extension or plugin that isn't working properly.<br /> Issues with the Enter key not working can be caused by the AVG Safe Search Toolbar. Start Firefox in [[Safe Mode]] to check if one of your add-ons is causing your problem (switch to the DEFAULT theme: Tools > Add-ons > Themes). * Don't make any changes on the Safe mode start window. See * [[Troubleshooting extensions and themes]] * [[Troubleshooting plugins]]