Start Firefox in Diagnose Firefox issues using Troubleshoot Mode to check if one of the add-ons is causing the problem (switch to the DEFAULT theme: Tools > Add-ons > Themes).

• Don't make any changes on the Safe mode start window.

See:

• Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems
• Troubleshoot issues with plugins like Flash or Java to fix common Firefox problems

If it does work in Safe-mode then disable all extensions and then try to find which is causing it by enabling one at a time until the problem reappears.

• Use "Disable all add-ons" on the Safe mode start window to disable all extensions.
• Close and restart Firefox after each change via "File > Exit" (Mac: "Firefox > Quit"; Linux: "File > Quit")

Your above posted system details show multiple Java Console extensions. You can uninstall (remove) the Java Console extensions, you do not need them to run Java applets.

See http://kb.mozillazine.org/Java#Multiple_Java_Console_extensions

Disable the Java Quick Starter extension: Tools -> Add-ons -> Extensions

• Control Panel -> Java -> Advanced tab -> Miscellaneous -> Java Quick Starter (disable)

See http://www.java.com/en/download/help/quickstarter.xml - What is Java Quick Starter (JQS)? What is the benefit of running JQS? - 6.0

Thanks for the reply Running in Safe Mode did not solve the problem. Themes are not activated. Disabled Java Console extension in Firefox & Control Panel - No Luck. Disabled Java Quick Starter - No Luck.

This is a puzzling problem because it started without any known changes - meaning new software, new extensions, etc.

I appreciate your thoughts & ideas.

Do a malware check with some malware scan programs.
You need to scan with all programs because each program detects different malware.
Make sure that you update each program to get the latest version of the database before doing a scan.

• 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 and What to do when searches take you to the wrong search website

Ran each of the spyware/malware programs with updates. Rebooted after each one. Ran Spybot a second time. Rebooted. And -- drum roll -- Success. Thanks so much. Based on the stuff in the errors, it is a strong likelihood that the culprit came from a "coupon" service via my eldest daughter. She had recently downloaded some software to facilitate printing coupons. She gets the discounts at the stores, I got the malware in my PC.

I had same problem it was the ASK menu bar add in. I disabled the ASK bar and now everything works fine

Had the same problem. Uninstalled the ASK toolbar and Firefox is now running fine again.

Ask toolbar seems to be the culprit for this problem. Thanks sahmiam

Thanks a lot! I was having the same problem too. After reading this post and its replies, I uninstalled the Pandora toolbar which somehow got installed of its own sometime, and now tabs are opening with CTRL+T and new tab button both..