https://support.mozilla.org/en-US/kb/websites-say-cookies-are-blocked-unblock-them
Many site issues can be caused by corrupt cookies or cache.
Warning ! ! This will log you out of sites you're
logged in to. You may also lose any settings
for that website.
If there is still a problem,
Start Firefox using Troubleshoot(Safe) Mode {web link}
A small dialog should appear. Click
Start In Troubleshoot(Safe) Mode (not Refresh).
Is the problem still there?
While you are in Troubleshoot(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}
https://support.mozilla.org/en-US/kb/websites-say-cookies-are-blocked-unblock-them
Many site issues can be caused by corrupt cookies or cache.
'''Warning ! ! ''' This will log you out of sites you're
logged in to. You may also lose any settings
for that website.
* [https://support.mozilla.org/en-US/kb/delete-cookies-remove-info-websites-stored Delete cookies to remove the information websites have stored on your computer] {web link}
* [https://support.mozilla.org/en-US/kb/how-clear-firefox-cache How to clear the Firefox cache] {web link}
If there is still a problem,
[https://support.mozilla.org/en-US/kb/diagnose-firefox-issues-using-troubleshoot-mode Start Firefox using Troubleshoot(Safe) Mode] {web link}
A small dialog should appear. Click
'''Start In Troubleshoot(Safe) Mode''' (not Refresh).
Is the problem still there?
While you are in Troubleshoot(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.
''[https://support.mozilla.org/en-US/kb/forum-response-disable-hardware-acceleration How to disable Hardware Acceleration]'' {web link}