Please give the web address and a screenshot of the problem. I did note a recent report that gmail was not working in Firefox:

https://support.mozilla.org/en-US/questions/1158315#answer-963608

Maybe you have security related software or scriptblockers that are causing the problem. Please review what additional software you may have and if necessary temporarily disable or uninstall it. Try in Firefox's safe mode. If that does not help try next in Windows own Safe Mode as well.
Please say exactly what happens and provide a screenshot or the exact wording of any message you are getting. See

• Diagnose Firefox issues using Troubleshoot Mode
• Disable or remove Add-ons
• Bleepingcomputer tutorial: https://www.bleepingcomputer.com/tutorials/start-windows-8-in-safe-mode/

Thank you John99. I attach the photo which show you the actual problem.

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You can reload web page(s) and bypass the cache to refresh possibly outdated or corrupted files.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

"Clear the cache":

• Firefox/Options/Preferences -> Advanced -> Network -> Cached Web Content: "Clear Now"

"Remove the cookies" from websites that cause problems.

• Firefox/Options/Preferences -> Privacy -> "Use custom settings for history" -> Cookies: "Show Cookies"

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 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

Yes it could be a javascript related problem.

When you post replies on this support forum do you see the buttons above where you post and do they work ok ?

For instance there is a

• [B] button for bold text
• Bulleted list item that I could have used to create these bullet points
  • (This was posted 3rd May whilst using Kitsune software - Just a note for long term forum users)

You are probably using some form of script blocking or add blocking software or add-on. Does using Firefox's safe mode help ?

• Diagnose Firefox issues using Troubleshoot Mode