Did you have Firefox 37.0 or 37.0.1 before you updated? The changes were very minor, so I think the problem is more along the lines of a glitch than a program change...

When you have a problem with one particular site, a good "first thing to try" is clearing your Firefox cache and deleting your saved cookies for the site.

(1) Bypass Firefox's Cache

Use Ctrl+Shift+r to reload the page fresh from the server.

Alternately, you also can clear Firefox's cache completely using:

"3-bar" menu button (or Tools menu) > Options > Advanced

On the Network mini-tab > Cached Web Content : "Clear Now"

If you have a large hard drive, this might take a few minutes.

(2) Remove the site's cookies (save any pending work first). While viewing a page on the site, try either:

• right-click and choose View Page Info > Security > "View Cookies"
• (menu bar) Tools > Page Info > Security > "View Cookies"
• click the padlock or globe icon in the address bar > More Information > "View Cookies"

In the dialog that opens, you can remove the site's cookies individually.

Then try reloading the page. Does that help?

Glitch is what I'd call it. I thought it would go away quickly, but it didn't. The Gmail page loads, and updates normally as new messages come in. I just can't click on them. Sometimes when I click a message it shows "Loading..." forever, sometimes it does nothing.

I haven't found any other problems, but Gmail is a huge part of my online life and key to everything I do for multiple organizations, so it has higher importance. At this point I'm using Chrome for email in a pinch, but if it continues I'll have to move almost all of my primary activity since I need to access several Google+ products and need to be able to access multiple Google+ log-ins simultaneously at times.

I can't tell from your reply whether you tried clearing cache and cookies and whether that made any difference.

If that doesn't help, the next thing to try is Firefox's Safe Mode. That's a standard diagnostic tool to deactivate extensions and some advanced features of Firefox. More info: Diagnose Firefox issues using Troubleshoot Mode.

If Firefox is not running: Hold down the Shift key when starting Firefox.

If Firefox is running: You can restart Firefox in Safe Mode using either:

• "3-bar" menu button > "?" button > Restart with Add-ons Disabled
• Help menu > Restart with Add-ons Disabled

and OK the restart.

Both scenarios: A small dialog should appear. Click "Start in Safe Mode" (not Refresh).

Any improvement?

No improvement, and yes, I cleared cookies and did a hard reload before my previous reply. Safe mode works exactly the same, so it's not he add-ons. I'll try it on another computer tomorrow, but if it isn't working on my laptop it is not very useful for me.