This issue can be caused by an extension that isn't working properly.

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

• Don't make any changes on the Safe mode start window.
• https://support.mozilla.com/kb/Safe+Mode

• https://support.mozilla.com/kb/Troubleshooting+extensions+and+themes

Also Remove Multiple Java Console extensions

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

Check and tell if its working.

Cor-el,

Thanks for your advice. The problem seems to have been the "Red Ladybug" persona. I've removed it and all (hopefully) seems to be OK.

I post a "solved".

Again, thanks

jamr

mha007,

Thanks for your help. There were 4 Java Console extensions. These have been disabled. The next question is - how do I remove these extensions?

Thanks again,

jamr

See the paragraph Multiple Java Console extensions in the article i provided in my previous post

mha007,

Thanks again. I didn't appreciate the significance of your earlier reply. I will get rid of them now.

cor-el, I thought this had been fixed with your extensions solution and mha007's recommendation to remove the old Java Console extensions.

The problem is still there. I'm not sure whether ZoneAlarm is an issue. When I check its compatibility the result is that it gets both a tick and a cross. The Compatibility Reporter itself says that it no longer works.

mha007, I thought this had been fixed with your and cor-el's solutions.

The problem is still there. I'm not sure whether ZoneAlarm is an issue. When I check its compatibility the result is that it gets both a tick and a cross. The Compatibility Reporter itself says that it no longer works.

If an extension isn't working and you see an error message then you shouldn't try to force that extension to install, but you should disable or remove such a malfunctioning extension.

• https://support.mozilla.com/kb/Troubleshooting+extensions+and+themes

If I disable ZoneAlarm in Extensions the problem goes away. However the ZoneAlarm system firewall (latest download earlier today) is still operating. What is the difference between the ZoneAlarm extension and the ZoneAlarm firewall? I don't mind admitting that I'm lost.

The ZoneAlarm firewall protect your computer against attacks from internet.
The ZoneAlarm extension for Firefox adds some extra features to Firefox that are usually not needed as Firefox has a build-in phishing protection.

See:

• http://www.mozilla.com/en-US/firefox/phishing-protection/

Thank you, cor-el, for your help and explanation of, and link detailing, the ZoneAlarm extension. ZoneAlarm, and its toolbar, are now disabled and everything is stable again.

I had the same problem with Firefox 6.0.2 but the Skype add-on would not show in add-on/extensions so I might disable it. I found that if I started Firefox in safe mode the Skype add-on would show and allowed me to disable it, there by clearing the problem. It's a shame that the Skype add-on doesn't have a remove option.