There is a conflict between title and question. The Back/Forward buttons only apply to going to a page that you have already been to within that tab -- that has nothing to do with between pages being on the same website. If you do not have pages in a direction that arrow is grayed out.

Problems:

• Corrupt localstore.rdf - MozillaZine Knowledge Base
  Back/forward can't be moved
  http://kb.mozillazine.org/Corrupt_localstore.rdf

second possibility

• Locked or damaged places.sqlite - MozillaZine Knowledge Base
  back/forward present but don't work
  http://kb.mozillazine.org/Locked_or_damaged_places.sqlite

Thanks, that is the problem, both arrows remain grey all of the time ,so, I cannot go back to a page that I had previously visited. Does this have to do with "Integer' which I may have to change from zero? If so how do I achieve this? Thanks

Thanks, that is the problem, both arrows remain grey all of the time ,so, I cannot go back to a page that I had previously visited. Does this have to do with "Integer' which I may have to change from zero? If so how do I achieve this? Thanks

Start Firefox in Diagnose Firefox issues using Troubleshoot Mode to check if one of the extensions or if hardware acceleration is causing the problem (switch to the DEFAULT theme: Firefox (Tools) > Add-ons > Appearance/Themes).

• Don't make any changes on the Safe mode start window.
• https://support.mozilla.com/kb/Safe+Mode

• https://support.mozilla.com/kb/Troubleshooting+extensions+and+themes

If you have "McAfee Site Advisor" you might save some time it that one is the problem ... Try specifically disabling "Site Advisor" extension see https://support.mozilla.com/en-US/questions/805964

If that is the problem you might be able to just re-enable it, but it would be better to uninstall through the control panel and reinstall "Site Advisor" as described in

http://kb.mozillazine.org/Problematic_extensions