Sometimes this problem is caused by an add-on which starts interacting with the page after most of the content loads, so you don't notice the problem until you get the message. The Skype Click-to-Call extension can have this issue.

In other cases, the problem may be caused by the page content itself.

Do you notice any pattern to the script that Firefox says is running slowly? Script names that start with chrome:// or resource:// refer either to parts of Firefox or an extension. Script names that start with http:// or https:// usually are part of the site you're visiting.

For additional information, you could try our support article: Warning Unresponsive script - What it means and how to fix it.

Another common cause of unresponsive script errors on Windows Vista and newer is the protected mode feature of the Flash player plugin. That feature has security benefits, but seems to have serious compatibility issues on some systems. You can disable it using the Add-ons page. Either:

• Ctrl+Shift+a
• "3-bar" menu button (or Tools menu) > Add-ons

In the left column, click Plugins. On the right side, find "Shockwave Flash" and click the More link. Then uncheck the box for "Enable Adobe Flash protected mode" and try that for a day to see whether it helps.

Did as advised and dis-enabled the Adobe Flash protected made. This seems to have solved thingds - no more annoying messages.

Many thanks