No problem here with FF57.0.3x64 Windows 10x64 Pro. Are you sure you didn't setup your 2 step security correctly? I can use Chrome and login to gmail without problem.

Here's what I see if I go to forget email.

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 57.0.4 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.

WestEnd I only get this problem on my laptop, so I think it is something specific to the set-up on that machine. Will try uninstalling and reinstalling Firefox as suggested by Pkshadow

Or could be a over aggressive A/V or Firewall that is blocking something from showing? Did you diable the A/V and Firewall and see what happens? Before we just wipe FF out to reinstall that should be last resort.

I don't know if Google's sliding login panels are affected by this setting, but just in case, please make sure the redirect block is turned off:

(1) In a new tab, type or paste about:config in the address bar and press Enter/Return. Click the button accepting the risk.

(2) In the search box above the list, type or paste access and pause while the list is filtered

(3) If the accessibility.blockautorefresh preference is bolded and "modified" or "user set" to true, double-click it to restore the default value of false

Also, if you see the "shield" icon at the left end of the address bar, indicating that Firefox has blocked "trackers" in the page, you may need to make an exception. More info in this article: What happened to Tracking Protection?.

Switching off AV/firewall did not help and the accessibility.blockautorefresh setting was false so I uninstalled FF, reinstalled FF57.0.4 and the problem seems to be solved, so thanks to all for their suggestions. Not sure if it is relevant but I had FF51 installed alongside FF57 before I removed both, so maybe this was an issue? Anyway, back in business now!