It could be the work of one of your add-ons. Type about:addons<enter> in the address bar to open your Add-ons Manager. Hot key; <Control> (Mac=<Command>) <Shift> A)

In the Add-ons Manager, on the left, select Extensions. Disable a few add-ons, then Restart Firefox.

Some added toolbar and anti-virus add-ons are known to cause Firefox issues. Disable All Of them.

If the problem continues, disable some more (restarting FF). Continue until the problem is gone. After, you know what group is causing the issue. Re-enable the last group ONE AT A TIME (restarting FF) until the problem returns.

Once you think you found the problem, disable that and re-enable all the others, then restart again. Let us know who the suspect is, detective.

Thank you for your reply.

I have no add-ons and no extensions.

Hello,

Try disabling graphics hardware acceleration in Firefox. Since this feature was added to Firefox it has gradually improved but there are still a few glitches.

You will need to restart Firefox for this to take effect so save all work first (e.g., mail you are composing, online documents you're editing, etc.,) and then perform these steps:

In Firefox 54 and below:

1. Click the menu button and select Options (Windows) or Preferences (Mac, Linux).
2. Select the Advanced panel and the General tab.
3. Uncheck Use hardware acceleration when available.
4. Close Firefox completely and then restart Firefox to see if the problem persists.

In Firefox 55 and above:

1. Click the menu button and select Options (Windows) or Preferences (Mac, Linux).
2. Select the General panel.
3. Under Performance, uncheck Use recommended performance settings. Additional settings will be displayed.

   

4. Uncheck Use hardware acceleration when available.
5. Close Firefox completely and then restart Firefox to see if the problem persists.

Did this fix your problems? Please report back to us!

If the problem is resolved, you should check for updates for your graphics driver by following the steps mentioned in these Knowledge base articles:

• Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems

• Upgrade your graphics drivers to use hardware acceleration and WebGL

Thank you.

Thank you for your latest reply.

Tried that too before I posted. That option isn't even present in that section of my options. I've uploaded a screenshot of my Performance section so you can see. . .

FredMcD said

3 Under Performance, uncheck Use recommended performance settings. Additional settings will be displayed.

Thank you for that information. I hadn't realized the hardware acceleration was in there.

But alas, did not fix the issue. And I cleared history.

cyngularcyn said

After the latest update of Firefox, I can no longer download or open any kind of file. Read the article on "Can't download. . .after update" and did all of the suggested fixes. Didn't fix it. Started Firefox in safe mode and everything worked. Went through all of the fixes for when the issue does not occur in safe mode and it didn't fix the issue. What else do you have?

Are you sure this isn't Firewall or A/V blocking? When you mean open any kind of file what you referencing this to?