Here is the screenshot

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

• Switch to the DEFAULT theme: Firefox/Tools > Add-ons > Appearance
• Do NOT click the Reset button on the Safe Mode start window

• https://support.mozilla.org/kb/Safe+Mode
• https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes

You can do a font test to see if you can identify font(s) that aren't working properly.

• http://browserspy.dk/fonts-flash.php?detail=1

You can try different default fonts and temporarily disable website fonts to test the selected default font.

• Tools > Options > Content : Fonts & Colors > Advanced
• [ ] "Allow pages to choose their own fonts, instead of my selections above"

Make sure to restore the default setting to allow websites to change fonts when you are done with testing.

cor-el said

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

• Switch to the DEFAULT theme: Firefox/Tools > Add-ons > Appearance
• Do NOT click the Reset button on the Safe Mode start window

• https://support.mozilla.org/kb/Safe+Mode
• https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes

---

You can do a font test to see if you can identify font(s) that aren't working properly.

• http://browserspy.dk/fonts-flash.php?detail=1

You can try different default fonts and temporarily disable website fonts to test the selected default font.

• Tools > Options > Content : Fonts & Colors > Advanced
• [ ] "Allow pages to choose their own fonts, instead of my selections above"

Make sure to restore the default setting to allow websites to change fonts when you are done with testing.

Nothing of this works :( and tested fonts and 452 are installed and all seems ok no problem there

Try to reset the page zoom on pages that cause problems.

• View > Zoom > Reset (Ctrl/Command+0 (zero))

• http://kb.mozillazine.org/Zoom_text_of_web_pages

You can delete possible user.js and numbered prefs-##.js files and rename (or delete) the prefs.js file to reset all prefs to the default value including prefs set via user.js and prefs that are no longer supported in the current Firefox release.

• http://kb.mozillazine.org/Preferences_not_saved
• http://kb.mozillazine.org/Resetting_preferences

You can use this button to go to the current Firefox profile folder:

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

Windows hides some file extensions by default. Among them .html and .ini and .js and .txt and you might only see a file name without file extension. You can check the file extension (type) in the Properties of the file in Windows Explorer via the right-click context menu.

Rana007 said

I have been searching a lot about this problem and have done a lot of things in about:config and even had it refreshed and clean installed from scratch but I am unable to solve the problem it happens on specific style of font and I don't know how to fix it back when looking in about:config I am sorry to say I really don't remember but I changed something which cleared the issue but some sites started showing a different problem the text was not displayed at all like on soundcloud the time showed during the playback of the track over the image of the sound wave was hidden this is just an example although I have my firefox restored and refreshed several times even did a new clean install but no help so please kindly help me with this annoying issue I would really hate to shift to any new browser just because of this issue The screen shot shows an example

cor-el said

Try to reset the page zoom on pages that cause problems.

• View > Zoom > Reset (Ctrl/Command+0 (zero))

• http://kb.mozillazine.org/Zoom_text_of_web_pages

---

You can delete possible user.js and numbered prefs-##.js files and rename (or delete) the prefs.js file to reset all prefs to the default value including prefs set via user.js and prefs that are no longer supported in the current Firefox release.

• http://kb.mozillazine.org/Preferences_not_saved
• http://kb.mozillazine.org/Resetting_preferences

You can use this button to go to the current Firefox profile folder:

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

Windows hides some file extensions by default. Among them .html and .ini and .js and .txt and you might only see a file name without file extension. You can check the file extension (type) in the Properties of the file in Windows Explorer via the right-click context menu.

Deleting user.js did the job thanks