Is this one page or all web pages? And got example sites?

No. Some examples are Uproxx.com and New York Daily News.com

They appear on screen for 1-2 seconds then everything disappears and all I'm left with is a blank white screen.

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

You see 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