Sometimes addons can cause this problem try see if this happens in safe mode: *[http://mzl.la/MwuO4X Firefox in safe mode] You can try create a new profile or reset Firefox preferences: *[http://mzl.la/LL5Dxl Manage profiles] *[http://mzl.la/MnSTZB Reset Firefox] Sometimes malwares also can cause this problems: *[http://mzl.la/MPPnpl Problems with malwares]

What page opens in a new tab? ---- Do a malware check with several malware scanning programs on the Windows computer. Please scan with all programs because each program detects different malware. All these programs have free versions. Make sure that you update each program to get the latest version of their databases before doing a scan. *Malwarebytes' Anti-Malware:<br>http://www.malwarebytes.org/mbam.php *AdwCleaner:<br>http://www.bleepingcomputer.com/download/adwcleaner/<br>http://www.softpedia.com/get/Antivirus/Removal-Tools/AdwCleaner.shtml *SuperAntispyware:<br>http://www.superantispyware.com/ *Microsoft Safety Scanner:<br>http://www.microsoft.com/security/scanner/en-us/default.aspx *Windows Defender:<br>http://windows.microsoft.com/en-us/windows/using-defender *Spybot Search & Destroy:<br>http://www.safer-networking.org/en/index.html *Kasperky Free Security Scan:<br>http://www.kaspersky.com/security-scan You can also do a check for a rootkit infection with TDSSKiller. *Anti-rootkit utility TDSSKiller:<br>http://support.kaspersky.com/5350?el=88446 See also: *"Spyware on Windows": http://kb.mozillazine.org/Popups_not_blocked

AlternaTIFF v2.0.6

Just for starters you might try disabling("Never activate") two of your plug-ins, one at a time, which seem to have caused occasional problems - AlternaTIFF v2.0.6 MetaStream 3 Plugin r4

I've never seen issues reported with the [http://www.alternatiff.com/ AlternaTIFF] plugin that is used to display TIFF image files that some website use (mainly patents).