What does the 'website scripts not responding' error message mean?

Q I use Firefox and I keep getting messages that say a ‘script is not responding’. How do I sort this out?
James Ducan

A We don’t have a lot to go on but the most common causes of this problem are errors contained within website scripts or one or more faulty add-ons.

We think it’s safe to assume that these script-error messages are happening on more than just the one website. As a first course of action we’d advise using Firefox’s Safe Mode option to disable all add-ons to see if this eliminates the problems.

To do this in Firefox 4, click the Firefox button, point to Help and then choose Restart With Add-ons Disabled. Alternatively, hold down the Shift key while launching Firefox.

In earlier versions of the browser, click Start then point to All Programs followed by Mozilla Firefox and click Firefox (Safe Mode).

In all cases, Firefox will launch by displaying its Safe Mode dialogue box (this has nothing whatsoever to do with Windows’ own Safe Mode).

This dialogue box has several options but the one we’re interested in is the top one, ‘Disable all add-ons’, so click to tick it and then click the Continue in Safe Mode button.

Now try surfing for a while, being sure to visit any websites that have previously led to script-error messages. If all is well, then it is fair to conclude that an ill-behaved add-on is indeed the cause of your frustration.

The job now is to find the perpetrator – and this will be a case of trial and error. To begin, restart Firefox so it is no longer in Safe Mode. Now click Tools and choose Add-ons. In the Extensions dialogue box, open the Tools menu and choose Disable All.

Now reactivate just one add-on by clicking its entry in the list below and clicking Enable followed by Restart Firefox. Again, try surfing to see if script errors occur. Then, rinse and repeat. If you have a lot of add-ons, this could take a while.

By doing this, we think you will probably finger one or more add-ons as the cause of the problem. Either disable or uninstall these (via the Extensions dialogue box discussed earlier) or check the relevant developers’ websites to see if there are any known issues or updates.