uninstall Firefox. Then Delete the Mozilla Firefox Folders in C:\Program Files and C:\Program Files(x86) 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 57.0.2 with a Full Version Installer

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

If issue persists make a new Profile and Test : https://support.mozilla.org/en-US/kb/profile-manager-create-and-remove-firefox-profiles

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

I had this exact same problem.

I tried all of the above solutions, but none worked.

Then I noticed that when I was on the Fandango seating map site, there was an icon in the address bar that indicated that the site was trying to "track" me, but was being denied (I had set up things so no site could track me).

Once I clicked on that and allowed Fandango to track me, I was able to finally see the seating map!