Hi, please try : uninstall Firefox. Then Delete the Mozilla Firefox Folders in C:\Program Files , C:\Program Files(x86) & C:\ProgramData Then restart system. Then run Windows Disk Cleanup. (Note: This should be Pinned and run Weekly, If never done below expect 10's of gig's) Then run it again and click the button that says Cleanup System Files. Note: your Firefox Profile is saved. But you should make a back up before you do :

• https://support.mozilla.org/en-US/kb/back-and-restore-information-firefox-profiles
• https://support.mozilla.org/en-US/kb/export-firefox-bookmarks-to-backup-or-transfer

Reinstall with Current Release Firefox 59.0.2 with a Full Version Installer

• https://www.mozilla.org/firefox/all/

Please let us know if this solved your issue or if need further assistance.

whatgives said

I can access site words only, no site view or normal screen. Warning says unsecured site, https.// does not work.

Is this the only HTTPS address giving you problems, or is it part of a larger pattern?

Firefox cannot actually tell whether the site is having a problem, even if it assumes that. Very often there is an intermediary between Firefox and the site that presents a "fake" site certificate, and that prevents Firefox from verifying that you are contacting the real server. The intermediary could be security software, or it could be malware.

not enough info to correct problem

whatgives said

not enough info to correct problem

Will say the same, what happened after trying my answer ?

Found add blocker was causing problem, turned off, all ok now.

Most such blockers can be set up to allow from sites that you select.