Certain Firefox problems can be solved by performing a Clean reinstall. This means you remove Firefox and any leftover program files and then reinstall Firefox. Please follow these steps one by one:

1. Download the latest Desktop version of Firefox from http://www.mozilla.org and save the setup file to your computer.
2. After the download finishes, close all Firefox windows (click Exit from the Firefox or File menu) and confirm all upcoming messages.
3. Now, uninstall Firefox by following the steps mentioned in the Uninstall Firefox article.

IMPORTANT: On Windows, the uninstaller has the option to remove your personal data and settings. Make sure that you do not check this option; otherwise all of your bookmarks, passwords, extensions, user customizations and other Firefox user profile data will be removed from your computer.

After uninstalling Firefox on Windows, delete the "Mozilla Firefox" program folder, located by default in one of these locations:

• (On 32-bit Windows) C:\Program Files\Mozilla Firefox
• (On 64-bit Windows) C:\Program Files (x86)\Mozilla Firefox

1. Go to the Windows Start menu and click on "Computer".
2. In the Explorer window that opens, double click Local Disk (C:) to open the C:\ drive.
3. Find the "Program Files (x86)" folder or "Program Files" folder.
   • On 32-bit Windows, double-click the Program Files folder to open it.
   • On 64-bit Windows, you will see a "Program Files (x86)" folder AND a "Program Files" folder. Open the Program Files (x86) folder.
4. Look for a Mozilla Firefox folder. If you find one, right-click it and select Delete and confirm that you want to move the folder to the Recycle Bin.

Now, go ahead and reinstall Firefox:

1. Double-click the downloaded installation file and go through the steps of the installation wizard.
2. Once the wizard is finished, choose to directly open Firefox after clicking the Finish button.

Please report back to see if this helped you!

Thanks for your answer.

i uninstalled Firefox from Add or Remove Programs in the control panel, then deleted it's leftovers from C:\Program Files\Mozilla Firefox (which is what I didn't do when I tried this before).

I reinstalled a new Firefox, and it has the same problems.

I'm now using Firefox Portable with no problems - but would sure like to be running the 'real thing'.

It is possible that anti-virus software is corrupting downloaded files or is otherwise interfering with downloading files.
Try to disable the real-time (live) scanning of files in your anti-virus software temporarily to see if that makes downloading work.

See:

• http://kb.mozillazine.org/Unable_to_save_or_download_files
• browser.download.manager.scanWhenDone

AV scanning or not or even completely disabled makes no difference.

Besides Firefox Portable, i also have Pale Moon, a derivative of Firefox, running reliably - and, of course, IE works.

Try to boot the computer in Windows Safe mode with network support (press F8 on the boot screen) as a test to see if that helps.

Sorry to take so long to answer. I tried to go to Safe Mode, but I think I have to find a non-USB keyboard. Used to have several.

Will get back here then.

Not windows Safe mode, Firefox Safe Mode.

The post I was responding to said,

"Try to boot the computer in Windows Safe mode with network support (press F8 on the boot screen) as a test to see if that helps. "

Somehow, I think that means Windows...

I've tried Firefox in Safe Mode - it makes no difference.

Did you try Windows Safe mode.

If that works then the problem is caused by other (security) software.

Ok, I've located a PS/2 keyboard, so I can boot to Safe Mode...

Referring to my original post, in Safe Mode, problem number 1 is not a problem - I can run or open anything from Downloads as Before Problems.

Problem 2 stays the same - I cannot print or go to Print Preview and I get the error messages as described in the first post above.

Problem 3 - I can't tell. It's updated to the latest version

Problem 4 - not a problem in Safe Mode. From Help|Troubleshooting Information, clicking the Reset Firefox button puts up a small dialogue box asking if I'm sure if I want to reset Firefox to it's original state, and that it will try to preserve History, bookmarks, passwords and more. Then another dialog box opens saying all those things it said it'd try to preserve were saved. Then Firefox starts and seems ok...

Also, clicking the Help|Troubleshooting Information|Show Folder button also now works.

Problem 5 is now Ok - dragging a url to the desktop or a folder makes a link to it, and dragging an image copies it to the desktop or a folder.

Problem 6 is ok, I can Browse for an image, and right click it to open it and see if it's ok.

So, as it sits, the only problem that persists in Safe Mode is #2, I can't print or go to Print Preview.

BUT, when I reboot out of Safe Mode...   all problems are back as before.

The problems it's having look as if Firefox wasn't really installed, but maybe(?) just copied in place - it seems Firefox doesn't know it's installed. I actually checked to see if Comodo was sandboxing it - but sandboxing is disabled in Comodo and I don't have any other sandboxing applications.

Again, I'm also running Firefox Portable as well as Pale Moon (A Firefox derivative), with no problems. Chrome & IE also run as they should. I downloaded these and more while these having these Firefox problems and everything else seems ok. I do not think my anti-virus software (avast!) is corrupting or otherwise interfering with downloading files.

I am fairly knowledgeable with Firefox and have used it since before it was called Firefox. I also participate in the Mozilla Thunderbird support forum, https://getsatisfaction.com/people/stan_647060.

What to try next?

Hello, any luck solving this issue ? I'm having the same problems with Firefox 20.0.1. Thanks

No luck at all.

I've completely removed Firefox, removed what was left in /Program Files as well as the profile. If there was anything in \Local Settings\Application Data that was also removed.

When it came out, I installed version 20, and it had all the same problems, so i completely removed it too.

I looked at the registry, and did a search for Firefox, and stopped counting and about 100 hits. I should probably clean them all out, but as I say up above I'm running Firefox Portable (from the hard drive) and have absolutely no problems with it. I also run Pale Moon which is an optimized Firefox.

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

I tried creating a new profile, and the problems persisted on it also.

When the problems first started, I signed in to another user account in Windows, and tried Firefox from there and was surprised that the problems were on it also - indicating it was not a profile problem.

I'm thinking the problem(s) come from registry key(s) that persist after Firefox and it's profiles are removed. If I had the guts I'd go through the registry and remove all 'Firefox' keys and then try to reinstall.