You have to give links so others can test to see if they get the same results.

Hi, please try a Refresh but Note that this does more than uninstalling and re-installing does. Normal uninstalling does not remove some preferences which may have become corrupt. Please Refresh but do this 1st:

• https://support.mozilla.org/en-US/kb/export-firefox-bookmarks-to-backup-or-transfer
• https://support.mozilla.org/en-US/kb/back-and-restore-information-firefox-profiles

then

• https://support.mozilla.org/en-US/kb/refresh-firefox-reset-add-ons-and-settings

Note: Any customization will revert back to default, you will also need to reinstall Extensions.

Please let us know if this solved your issue or if need further assistance.

Thank you for your help! I did already all the things which are mentioned in the advises, with no result. I must emphasize that this problem only occurs Mavericks/Firefox 61-0.1. On my other computer, El Capitan, it is not a problem. This is one of the sites where the problem occurs: http://mac-torrents.com/category/mac-os-apps/

I think I know the reason: Firefox blocs this site, because it is regarded as unsafe for mixed content. As far as I understand especialy for images. Strange that Firefox on other systems hasn't any objection. Nor other browsers have. The only question remains: how can I debloc permenantly a site (especialy when I know that the site is safe)

This happens when CSS files fail to load properly.

If you use extensions ("3-bar" menu button or Tools -> Add-ons -> Extensions) that can block (wanted) content (Adblock Plus, NoScript, Disconnect, Ghostery, Privacy Badger, uBlock Origin) always make sure such extensions do not block (wanted) content.

• make sure your extensions and filters are updated to the latest version
• https://support.mozilla.org/en-US/kb/troubleshoot-extensions-themes-to-fix-problems

Firefox shows the shield icon at the left end of the location/address bar in case content is blocked by Tracking Protection.

• click the shield icon for more detail and possibly disable the protection
• check the Web Console for more detail about what content is blocked by Tracking Protection
• "3-bar" menu button or Tools -> Web Developer

• https://support.mozilla.org/en-US/kb/tracking-protection-firefox

You can try these steps in case of issues with web pages:

You can reload web page(s) and bypass the cache to refresh possibly outdated or corrupted files.

• hold down the Shift key and left-click the Reload button
• press "Ctrl + F5" or press "Ctrl + Shift + R" (Windows,Linux)
• press "Command + Shift + R" (Mac)

Clear the Cache and remove the Cookies from websites that cause problems via the "3-bar" Firefox menu button (Options/Preferences).

"Remove the Cookies" from websites that cause problems:

• Options/Preferences -> Privacy & Security
  Cookies and Site Data -> Manage Data

"Clear the Cache":

• Options/Preferences -> Privacy & Security
  Cookies and Site Data -> Clear Data -> Cached Web Content: Clear

Start Firefox in Safe Mode to check if one of the extensions ("3-bar" menu button or Tools -> Add-ons -> Extensions) or if hardware acceleration is is causing the problem.

• switch to the DEFAULT theme: "3-bar" menu button or Tools -> Add-ons -> Appearance
• do NOT click the "Refresh Firefox" button on the Safe Mode start window

• https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-using-safe-mode
• https://support.mozilla.org/en-US/kb/troubleshoot-extensions-themes-to-fix-problems

@cor-el I'm very grateful to you!!!! This solved the problem. This topic is resolved!

I must add the real cause: the DuckDuckGo Essentials (addon) was the real cause. When deleted everything became ok. Btw: a good alternative for DuckDuckGo is (anonymous) Searchmachine Startpage