Please explain the problem in detail. What happens? What is/are the exact error message(s) ?

When I click on the bookmark, or manually enter the URL, it looks like it's going to load the page by the info in the lower left corner of the browser, and then it just stalls; every other bookmark or tool works, just can't load the key bank page. It loads just fine in Safari. There are no error messages, just a white blank page.

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

• check the permissions for the domain in the currently selected tab in "Tools -> Page Info -> Permissions"
• https://support.mozilla.org/en-US/kb/fix-login-issues-on-websites-require-passwords

If you use extensions ("3-bar" menu button or Tools -> Add-ons -> Extensions) that can block content (Adblock Plus, NoScript, Disconnect, Ghostery, Privacy Badger, uBlock Origin) always make sure such extensions do not block content.

• make sure your extensions and filters are updated to the latest version
• https://support.mozilla.org/en-US/kb/troubleshoot-extensions-themes-to-fix-problems

Firefox shows a purple shield instead of a gray shield at the left end of the location/address bar in case Enhanced Tracking Protection is blocking content. You can click shield icon for more detail and possibly disable the protection. You can check the Web Console for messages about blocked content.

• https://support.mozilla.org/en-US/kb/enhanced-tracking-protection-firefox-desktop
• https://support.mozilla.org/en-US/kb/trackers-and-scripts-firefox-blocks-enhanced-track

You can try these steps in case of issues with web pages:

You can reload web page(s) and bypass the cache to refresh possibly outdated or corrupted files.

• hold down the Shift key and left-click the Reload button
• press "Ctrl + F5" or press "Ctrl + Shift + R" (Windows,Linux)
• press "Command + Shift + R" (Mac)

Clear the Cache and remove the Cookies for websites that cause problems via the "3-bar" Firefox menu button (Options/Preferences).

"Remove the Cookies" for websites that cause problems:

• Options/Preferences -> Privacy & Security
  Cookies and Site Data: "Manage Data"

"Clear the Cache":

• Options/Preferences -> Privacy & Security
  Cookies and Site Data -> Clear Data -> Cached Web Content: Clear

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 or userChrome.css is causing the problem.

• switch to the DEFAULT theme: "3-bar" menu button or Tools -> Add-ons -> Themes
• 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
• https://support.mozilla.org/en-US/kb/enhanced-tracking-protection-firefox-desktop
• https://support.mozilla.org/en-US/kb/trackers-and-scripts-firefox-blocks-enhanced-track

Thank you for such a thorough response. Unfortunately, none of these things helped. I contacted key bank again, because it is only the key bank site that will not load. All my other banking and finance (and other) bookmarks work as usual. I've tried clearing the cache, the cookies; reinstalling Firefox, etc to no avail. Everything that should be enabled is enabled in permissions and security. I've tried loading the login page on keybank manually (avoiding the bookmarked url)- same thing. There is no error message, it simply won't load; key bank wants an error code to go by to evaluate the problem, but there is one. The browser doesn't freeze up; you can close the tab and click on anything else- everything else works just fine. The Keybank representative says that Firefox gives them problems quite a bit. In all the years using Mozilla, I've never had this problem, so I would deduce that it is a keybank issue as none of my other sites are affected.

 I'm at a loss, but it's not the end of the world- just a minuscule inconvenience as I can use my mobile connection or Safari to access my account. It just doesn't make sense

here's a screen shot of what I get when I try to log in, center circle just rotates and rotates; nothing happens

also, fyi, I tried loading firefox in safe mode- still not able to load site

Start your Computer in safe mode with network support. Then start Firefox. Try Secure websites. Is the problem still there?

http://encyclopedia2.thefreedictionary.com/Linux+Safe+Mode Starting Any Computer In Safe Mode; Free Online Encyclopedia

it is a secure website and I tried starting Firefox in safe mode. Every other site/bookmark works. It's something with the Keybank/Firefox connection even if they won't acknowledge it

. . . and I tried starting Firefox in safe mode.

Start your Computer in safe mode with network support.

Well I guess that was worth a try; didn't make much sense that for one site malfunctioning when everything else worked that booting the whole machine in safe mode would do anything...and it didn't ...

 Thanks anyway!

I refreshed the browser again and this time it seemed to cure the key bank dilemma

Interesting. That was very good work. Well Done. Please flag your last post as Solved Problem as this can help others with similar problems.