Start Firefox in Safe Mode to check if one of the extensions ("3-bar" menu button or Tools -> Add-ons -> Extensions) or if hardware acceleration is is causing the problem.

• switch to the DEFAULT theme: "3-bar" menu button or Tools -> Add-ons -> Appearance
• do NOT click the "Refresh Firefox" button on the Safe Mode start window

• https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-using-safe-mode
• https://support.mozilla.org/en-US/kb/troubleshoot-extensions-themes-to-fix-problems

You can remove all data stored in Firefox from a specific domain via "Forget About This Site" in the right-click context menu of an history entry ("History -> Show All History" or "View -> Sidebar -> History").

Using "Forget About This Site" will remove all data stored in Firefox from this domain like history and cookies and passwords and exceptions and cache, so be cautious. If you have a password or other data from that domain that you do not want to lose then make sure to backup this data or make a note.

You can't recover from this 'forget' unless you have a backup of involved files.

If you revisit a 'forgotten' website then data from that website will be saved once again.

• https://support.mozilla.org/en-US/kb/delete-browsing-search-download-history-firefox

Hi, there are really ridiculous things that can stop connecting to just 1 site. Extensions that block needed data/cookies to java scripts. So adblockers/Private Browsing is one/two and then there is Security Programs as well as ..... Ok, I like going for the gusto on Win10 Suggestions of issues and to go for a clean reinstall and there is no perfect time than now as Firefox updates to version 62, today.

So if you could please follow along with some trust will get you to 62.0 and not saying will fix the issue but hoping to.

So, Win 10 responds real well to this so please  : 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 62.0.0 with a Full Version Installer ((( not today *https://www.mozilla.org/firefox/all/)))) Pick your language : https://ftp.mozilla.org/pub/firefox/releases/62.0/win64/ Please let us know if this solved your issue or if need further assistance.

Hi, this was linked to "Ghostery" a no tracker / no ad extension. By deactivating it I could connect to Twitter. Then I reactivated it and I could also connect to Twitter.

Thansk cor-el and Pkshadow for your help.