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 cautious not to copy corrupted files to avoid carrying over the problem.

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

See also:

• "Hang at exit": http://kb.mozillazine.org/Firefox_hangs
• "Firefox hangs when you quit it": https://support.mozilla.org/kb/Firefox+hangs

Thank you for the quick reply. It will take me longer to investigate as I'm on holiday. Will get back if/when I resolve the problems.

Hi Lochaber!!!! If I am understanding your situation correct, it seems that after closing Firefox after using it, the PC still says it is open and running.

Try restarting the PC by performing a hard reboot. http://www.ehow.com/how_6824847_do-pc-hard-reboot.html link text

1.) Click "Start" and go to "Shut down." 2.) Wait for PC to shut down. 3.) Remove Power Cord. 4.) Wait 2 minutes. 5.) Replace Power Cord and restart PC.

If the above step, doesn't "close" the browser then you would want to end the process in the task manager. Here's the link and the steps to end the process in the task manager:

https://support.mozilla.org/en-US/kb/firefox-already-running-not-responding link text

1.) Right click empty spot in Task bar and select "Task Manager." 2.) Select "'Processes'" Tab. 3.) Select the entry for Firefox.exe (press F on the keyboard to find it) and click End Process. 4.) Click Yes. 5.) If needed, repeat above steps for additional processes. Otherwise, exit Task Manager. 6.) Start Firefox

If you need to delete your profile, in Firefox, to ensure that Firefox starts properly next time you use it, here's how to find it in Firefox:

https://support.mozilla.org/en-US/kb/profiles-where-firefox-stores-user-data#w_finding-your-profile-without-opening-firefox link text

1.) At the top of the Firefox window, click on the Firefox button, go over to the Help menu and select Troubleshooting Information. The Troubleshooting Information tab will open.

2.) Under the Application Basics section, click on Show Folder. A window with your profile files will open.

If you need to find your profile, without opening the browser:

1.) Click the Windows Start button and type %APPDATA%\Mozilla\Firefox\Profiles\ in the Search box at the bottom of the Start menu, without pressing Enter. A list of profiles will appear at the top of the Start menu.

2.) Click on the profile with “default” in the name to open it in a window.

Thank you for your suggestion. If I want to close firefox then restart it is only 'sometimes' it fails. Occasionally it needs a few seconds before it will restart. If it says firefox still running, after say 20 seconds, I go to Task Manager and close it. This is where I see the ~25% CPU being used After that it works ok. I'm using an Acer Laptop, not PC.

This is a minor problem but the slowing down is my first priority as it will hopefully avoid needing to restart... I hope! It's only recently I've been online for long periods.

Did you look at these articles?

• "Hang at exit": http://kb.mozillazine.org/Firefox_hangs
• "Firefox hangs when you quit it": https://support.mozilla.org/kb/Firefox+hangs

Sometimes Firefox may need more time to close completely especially if you also clear data via "Clear history when Firefox closes" or have run a long session with a lot of visited pages.

It is also possible that there is a hanging Firefox or plugin-container process showing in the Task Manager.

• Use "Firefox > Exit" (Windows: Firefox/File > Exit; Mac: Firefox > Quit Firefox; Linux: Firefox/File > Quit) to close Firefox if you are currently doing that by clicking the close X on the Firefox title bar.

Thanks for the suggestions, sorry for the long delay getting back here. I was abroad and using the laptop and wanted to allow time to see if the problem was resolved. In the end I didn't see much changed with a new Profile.

I'm now running Firefox 29.0.1.

What I have noticed is the home PC also exibits a slowing down and sometimes I have to stop Firefox via the Task Manager.

I can live with the problems but do wonder if it's tied up with the way I use the computers.

I frequently close the laptop using "Hibernate" when abroad and at home I usually use "Sleep" on the PC.

I'm now on the PC and find that closing Firefox and restarting will usually help. When reading the news pages online I open many Tabs (10?), to read later, and wonder if this too may be contributing to the problem?

Your System Details shows;

Installed Plug-ins

Shockwave Flash 12.0 r0 Shockwave Flash 11.9 r900

From what I have been reading from other posts on this forum, the issue may be caused by the clear history settings.

Press the <Alt> or <F10> key to bring up the tool bar. Followed by;

Windows; Tools > Options Linux; Edit > Preferences Mac; application name > Preferences

Then Privacy.

The button next to History, select Use Custom Settings.

At the bottom of the page, turn on Clear History When Firefox Closes. At the far right, press the Settings button. Turn on ONLY Cache and Form And Search History leaving the others off.

This is not a cure but will make it easier if Firefox locks up. https://support.mozilla.org/questions/997866?esab=a&s=&r=1&as=s {web link}

Previously set up as above!