While Firefox is running, it will be using the cookies.sqlite file. Is that the file you want to delete? Make sure you completely exit out of Firefox and allow some time (10 seconds?) for Firefox to shut down and release files. Then try deleting again.

And/or, you could provide more information on what's going on to see whether there are other steps we would recommend.

Thank you, I hesitate to delete this type of file as I don't want to make any fundamental changes to my computer! So perhaps if I could ask for further assistance with the steps to troubleshoot removing corrupt cookies?

It gives the following steps which I don't understand as I get stuck at #3 (I don't know where the menu button is in that particular screen).

Open your profile folder:

1. Click the menu button , click help and select Troubleshooting Information. The Troubleshooting Information tab will open.

2. Under the Application Basics section, click on Show FolderOpen FolderShow in FinderOpen Directory. A window with your profile filesfolder will open.

3. Click the menu button then click ExitQuit .

4. Delete the cookies.sqlite file and any cookies.sqlite-journal files.

5. Restart Firefox.

... Further to the above problem, this arose due to problems with some pages that require username and passwords not loading where the loading wheel also continuously keeps turning. thx!

Okay, yes, clearing Firefox's cache (like "temporary internet files") and the relevant cookies, can help with website problems. But you usually don't need to physically delete the cookies database. Here's how I usually describe those steps:

When you have a problem with one particular site, a good "first thing to try" is clearing your Firefox cache and deleting your saved cookies for the site.

(1) Clear Firefox's Cache

See: How to clear the Firefox cache

If you have a large hard drive, this might take a few minutes. If you do not see the number going down on the page, you can reload it using Ctrl+r to check progress.

(2) Remove the site's cookies (save any pending work first). While viewing a page on the site, try either:

• right-click (on Mac Ctrl+click) a blank area of the page and choose View Page Info > Security > "View Cookies"
• (menu bar) Tools > Page Info > Security > "View Cookies"
• click the padlock or "i" icon in the address bar, then the ">" button, then More Information, and finally the "View Cookies" button

In the dialog that opens, the current site should be pre-filled in the search box at the top of the dialog so you can remove that site's cookies individually.

Then try reloading the page. Does that help?

Other factors that may affect pages loading include:

• Tracking Protection, a feature Firefox applies automatically in private windows. There's a shield icon toward the left end of the address bar when tracking protection is blocking some content. More info in this article: What happened to Tracking Protection?

• Add-ons that filter/block selected content, whether ads, scripts, or other content. You can test the site in Firefox's Safe Mode as a way to assess whether this is a factor.

In its Safe Mode, Firefox temporarily deactivates extensions, hardware acceleration, and some other advanced features to help you assess whether these are causing the problem.

If Firefox is not running: Hold down the Shift key when starting Firefox.

If Firefox is running: You can restart Firefox in Safe Mode using either:

• "3-bar" menu button > "?" button > Restart with Add-ons Disabled
• Help menu > Restart with Add-ons Disabled

and OK the restart.

Both scenarios: A small dialog should appear. Click "Start in Safe Mode" (not Refresh).

Any improvement? (More info: Diagnose Firefox issues using Troubleshoot Mode)

Before trying the above steps I went on another tangent and uninstalled firefox but now can't re-install it. So will need to do that before attempting the above. (When I hit the download button in Chrome nothing happens). Again, original problem is: Not being able to open certain websites (usually ones that require username and passwords). (I'm using Chrome right now...) thx

Can you download from this page (scroll down to your preferred language):

https://www.mozilla.org/firefox/organizations/all/

Stick with the regular Windows Firefox (32-bit) if you need any plugins other than Flash (e.g., Adobe, Java, etc.). If you decide to switch to 64-bit, see: How to switch from 32-bit to 64-bit Firefox.

Can you download/install from that page?

Note that the OP is on Windows Vista and thus can only use a 32-bit Firefox version.

Keep in mind that a reset tries to import cookies and thus may carry over cookie issues.

Note that you can rename cookies.sqlite to cookies.sqlite.old with with Firefox closed to be able to undo this action.

You can use the button on the "Help -> Troubleshooting Information" (about:support) page to go to the current Firefox profile folder or use the about:profiles page.

• Help -> Troubleshooting Information -> Profile Directory:
  Windows: Show Folder; Linux: Open Directory; Mac: Show in Finder
• http://kb.mozillazine.org/Profile_folder_-_Firefox