That is not a built-in feature of Firefox. First check to see if an add-on is causing this, to do that follow the procedure in the [[troubleshooting extensions and themes]] article. Also check to see if that bar is part of a site that is stored as a home page, if it is you can change the home page, for details see [[how to set the home page]]. I am not aware of any malware that behaves like this, but to be safe try running several malware scanners. It is best to run several as each will pick up things that the others miss. Some scanners you can try are: * [http://www.malwarebytes.org/mbam.php Malwarebytes] * [http://www.superantispyware.com/ SUPERAntiSpyware] * [http://www.lavasoft.com/products/ad_aware_free.php Ad-Aware] * [http://www.microsoft.com/windows/products/winfamily/defender/default.mspx Windows Defender] * [http://www.safer-networking.org/en/home/index.html Spybot S&D]