Load the web page. Then, to reload the page bypassing the cache and force a fresh retrieval; Ctrl+Shift+R (Mac=Command+Shift+R)

Many site issues can be caused by corrupt cookies or cache.

• Clear the Cache and
• Remove Cookies

Warning ! ! This will log you out of sites you're logged in to. You may also lose any settings for that website.

• Cookies; Delete cookies to remove the information websites have stored on your computer {web link}

• Cache; How to clear the Firefox cache {web link}

If there is still a problem, Start Firefox in Safe Mode {web link} by holding down the <Shift> (Mac=Options) key, and then starting Firefox.

A small dialog should appear. Click Start In Safe Mode (not Refresh). Did this help?

While you are in safe mode;

Try disabling graphics hardware acceleration in Firefox. Since this feature was added to Firefox it has gradually improved but there are still a few glitches.

How to disable Hardware Acceleration {web link}

I reloaded the webpage with ctrl+shift+R, as you described. I deleted cookies and cleared the cache, as described above. I also disabled graphics hardware acceleration in Firefox. Soon I had the same problem, now with googe Drive (see picture below). There's no point at that time restarting Firefox in safe mode, since I already told that any reload of the web page solves the problem. It's just the first time that seemingly a random web page loads, part or all of the content on the lower side is not shown.

Start your Computer in safe mode with network support. Then start Firefox. Try Secure websites. Is the problem still there?

http://encyclopedia2.thefreedictionary.com/Linux+Safe+Mode Starting Any Computer In Safe Mode; Free Online Encyclopedia

I used my PC for almost 2 days in safe mode with network support and had no problems with incomplete web pages. Of course, this doesn't proof anything, since I already said that the problem occurs only now and then, and never twice in succession. And since it is to annoying and limiting to keep using my computer in safe mode for a long time, I think I will just accept this bug and be satisfied with renewing the webpage every now and then. Thanx

As a test, disable your protection programs. What are you using?

I use Bitdefender Total Security. I'll let you know if this helps but it can take a while to be sure.

If you think Bitdefender is causing the issue, contact its support.

OK, will do.

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

Some days ago I noticed under Task Management (CTRL+SHIFT+ESC) that firefox.exe was opened 5 and sometimes 6 times. Why is that necessary? Today I accidently opened a link to a web page 2 times rapidly after each other since it didn't open right away. Then I noticed that same webpage was opened in 2 tabs (which was to be expected), but the second tab was blank again, like the example pictures erlier above, and the first one was ok. Does this ring a bell to anyone? Because on earlier times when I opened a web page accidently 2 times, it mostly opened only one time correctly, and one time incomplete. Make no mistake, the problem I started discussing concerns an only ones opened webpage. But could there be a connection?

You may see three or more Firefox processes running.

• one process for the main Firefox thread (user interface)
• one or more content processes set via dom.ipc.processCount
  Options/Preferences -> General -> Performance
  remove checkmark: [ ] "Use recommended performance settings"
• one process for the compositor thread (Windows;graphics)

You can check "Help -> Troubleshooting Information" (about:support) to see the current multi-process state.

• "Help -> Troubleshooting Information" -> "Application Basics":
  Multiprocess Windows
  Web Content Processes

See also:

• https://support.mozilla.org/en-US/kb/performance-settings