Are you able to paste the full error message into your next post please.

• See Warning Unresponsive script - What it means and how to fix it
  • and http://kb.mozillazine.org/Unresponsive_Script_Warning#Finding_the_source_of_the_problem

The above article explains that the Firefox error console should display the error message, and it is probably best to clear the console messages before you start a download. The articles list some of the common causes of this problem.

Also try other sites, is it only one site that causes the problem?

I am not able to get anything I click on to respond at all. However, the remaining part of the warning is:

Script: resource://gre/modules/NetworkPrioritizer.jsm:143

Thank you for your quick response and all of your help.

defrag HD, --- you may suffer from overload!

That looks to be Firefox's internal code.

• Presumably you have tried waiting longer to see if it completes ?
• Do you only get the error from the one site ?
• Can you try downloading files of a similar size,number,and type from some alternative site. Does that work ?

As for how to get out of the situation, you may need to kill the Firefox process. (Not sure how that is done on a Mac)

• but see "Firefox is already running but is not responding" error - How to fix_end-firefox-processes

As a basic and simple troubleshooting step please try Firefox in Safe Mode

• Diagnose Firefox issues using Troubleshoot Mode
• and if that does not help try the general download resets
  What to do if you can't download or save files

 _{? bug 476541}

I do not have a Mac

As an experiment try out this:

Following the steps will hang the browser completely:
1) Load https://bugzilla.mozilla.org/attachment.cgi?id=351645
2) Hit Cmd+S before the alert comes up
3) Wait...

While staying in step 3 you will see that the alert sheet is positioned under the save dialog. When this happens there is no way to close the save dialog. The browser has to be killed.

When I try the above I have no problem.

1. I see the word test,
2. I get a prompt to close the test.
3. The test re-displays, but the tab may be closed, and the browser does not hang.

If you have a problem with the above it is apparently a known bug.

I could not post these details yesterday as I needed access to bugzilla and it was down for maintenance because it was being updated.

P.S.

CARE

This test is likely to lock up your browser, in a similar way to the downloads problem so do not do it while in the middle of anything important.

This is the first chance I've had to try your experiment. Today when I opened my iMac there was a Software Update box. Clicking on the Ask Later or the Update Firefox buttons doesn't do anything. When I follow your instructions I get what you do, however, I am able to close the 'Save' dialog box. And I am still unable to close the Firefox boxes.

I appreciate your continued help, I am an old guy just joining the 21st century and not very tech savvy. Thank you.

Start Firefox in Safe Mode to check if one of the extensions (Firefox/Tools > Add-ons > Extensions) or if hardware acceleration is causing the problem (switch to the DEFAULT theme: Firefox/Tools > Add-ons > Appearance).

• Do NOT click the Reset button on the Safe mode start window or otherwise make changes.

• https://support.mozilla.org/kb/Safe+Mode
• https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes

Are you running anti-virus software on your Mac?

No, I am not running any anti-virus software. Only what Mediacom provides.

This problem is very frustrating, I have tried each suggestion several times to no avail.

Try to delete the downloads.sqlite file and the mimeTypes.rdf file in the Firefox profile folder.

You can use this button to go to the Firefox profile folder:

• Help > Troubleshooting Information > Profile Directory: Show Folder

Try to create a new profile as a test to check if your current profile is causing the problems.

See "Creating a profile":

• https://support.mozilla.org/kb/profile-manager-create-and-remove-firefox-profiles
• http://kb.mozillazine.org/Standard_diagnostic_-_Firefox#Profile_issues

If the new profile works then you can transfer some files from an existing profile to the new profile, but be careful not to copy corrupted files.

• http://kb.mozillazine.org/Transferring_data_to_a_new_profile_-_Firefox