• "Clear the Cache": Tools > Options > Advanced > Network > Offline Storage (Cache): "Clear Now"
• "Remove the Cookies" from sites that cause problems: Tools > Options > Privacy > Cookies: "Show Cookies"

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

This worked for me. It seemed one of my add-ons called "Relevant Knowledge" was the culprit. I'm not even sure what this add-on is or when I even installed it. But it doesn't appear to be necessary as Firefox is working fine for me now.

It is the "Relevant Knowledge" Add On. It's Spyware. If you disable it and restart FireFox it'll allow you to browse again. Then you'll want to do how to remove it.

EHow suggests just uninstalling from control panel > Uninstall programs. http://www.ehow.com/how_5634500_remove-relevant-knowledge-spyware.html

I suggest you download Malware Bytes which has saved my butt a few times. Reason being, I've also seen a few threads which suggest you must remove this from your registry. Perform a quick scan firt. Then full later. I'm running one now and it's alredy found a couple (28) of issue from this "Relevant Knowledge Spyware."

Also, this is how it was installed on my machine. I downloaded a "Free Flash Video Converter" from LEAWO.COM and installed their software. That's when it was placed onto my cpu. I can verify that 2 other machines in my office were infected when downloading this software from their company. Advice is to stay away http://www.leawo.com until they shape up. Their software was great though.

Note: One employee when downloading, was prompted by her anti virus that something was amiss.