PS: I "checked" settings, whatever that is supposed to mean, changed the password to be safe and restarted the computer. Cache and cookies are cleared. I'm using OSX 10.10.5, FF 40.0.3. THANKS !

This issue can be caused by corrupted cookies or cookies that are blocked.

• check the permissions on the about:permissions page and in "Tools > Page Info > Permissions"
• https://support.mozilla.org/kb/fix-login-issues-on-websites-require-passwords

Clear the cache and remove cookies only from websites that cause problems.

"Clear the Cache":

• Firefox > Preferences > Advanced > Network > Cached Web Content: "Clear Now"

"Remove Cookies" from sites causing problems:

• Firefox > Preferences > Privacy > "Use custom settings for history" > Cookies: "Show Cookies"

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

• Switch to the DEFAULT theme: Firefox menu button/Tools > Add-ons > Appearance
• Do NOT click the Reset button on the Safe Mode start window

• https://support.mozilla.org/kb/Safe+Mode
• https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes

E808 said

God I wish I had an free alternative to yahoo mail.

They are out there. Some are better than others.

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

How will I know which Add-on or Extension it might be? Thanks!

@Fred McD Any recommendations would be appreciated. Am getting ready to go vpn - any recommendations on how to find the best, ad-free secure email, free or not? Ideally free, like, maybe the Mozilla crew has kindly created one? I'd happily donate to the cause!

E808 said

How will I know which Add-on or Extension it might be? Thanks!

Trial and error.

E808 said

any recommendations on how to find the best, ad-free secure email

Many providers have e-mails. I use Microsoft. I don't know if your Mac will be allowed. Live.com

It could be the work of one of your add-ons. Type about:addons<enter> in the address bar to open your Add-ons Manager. Hot key; <Control>(Mac:<Command>)<Shift> A)

In the Add-ons Manager, on the left, select Extensions. Disable a few add-ons, then Restart Firefox.

Some added toolbar and anti-virus add-ons are known to cause Firefox issues. Disable All of them.

If the problem continues, disable some more (restarting FF). Continue until the problem is gone. After, you know what group is causing the issue. Re-enable the last group ONE AT A TIME (restarting FF) until the problem returns.

Once you think you found the problem, disable that and re-enable all the others, then restart again. Let us know who the suspect is detective.

Ok, I'll dive into trial and error. Thank you for your help!