Do a malware check with some malware scanning programs.<br /> You need to scan with all programs because each program detects different malware.<br /> Make sure that you update each program to get the latest version of their databases before doing a scan.<br /> <br /> * http://www.malwarebytes.org/mbam.php - Malwarebytes' Anti-Malware * http://www.superantispyware.com/ - SuperAntispyware * http://www.microsoft.com/windows/products/winfamily/defender/default.mspx - Windows Defender: Home Page * http://www.safer-networking.org/en/index.html - Spybot Search & Destroy * http://www.lavasoft.com/products/ad_aware_free.php - Ad-Aware Free See also: * "Spyware on Windows": http://kb.mozillazine.org/Popups_not_blocked ---- There are other things that need your attention. Your above posted system details show outdated plugin(s) with known security and stability risks that you should update. *Shockwave Flash 10.0 r45 Update the Flash plugin to the latest version. *https://support.mozilla.com/kb/Managing+the+Flash+plugin *http://kb.mozillazine.org/Flash *http://www.adobe.com/software/flash/about/ Update the Java plugin to the latest version. *https://support.mozilla.com/kb/Using+the+Java+plugin+with+Firefox *http://kb.mozillazine.org/Java *http://www.oracle.com/technetwork/java/javase/downloads/index.html (Java Platform: Download JRE)