That report was from a crash after a shutdown hang in April. A related bug was filed Bug 1143866. It appears that was a regression and disappeared again in later versions of Firefox.

You mention Windows reports relating to Firefox 39, have you got any Firefox crash reports from Firefox 39.

• bp-4056fb16-31ca-4847-8332-a05592150417
• Bug 1143866 - crash in shutdownhang | WaitForSingleObjectEx | WaitForSingleObject | PR_WaitCondVar | PR_JoinThread | mozilla::dom::DOMStorageDBThread::Shutdown()

Here's the most recent crash report in the server's event logs:

The program firefox.exe version 41.0.1.5750 stopped interacting with Windows and was closed. To see if more information about the problem is available, check the problem history in the Action Center control panel.

Process ID: 1de0
Start Time: 01d0fbb0e3eb46b2
Termination Time: 267
Application Path: C:\Program Files (x86)\Mozilla Firefox\firefox.exe
Report Id: f5d60fd9-6882-11e5-811a-00155dc8d9d2
Faulting package full name: 
Faulting package-relative application ID:

When I have the user's run About:Crashes in Firefox after a crash, they get a page that says "No Crash Reports Have Been Submitted"

Start Firefox in Safe Mode {web Link} by holding down the <Shift>
(Mac Options) key, and then starting Firefox. Is the problem still there?

Start your Computer in safe mode with networking. Then start Firefox. Try Safe web sites. Is the problem still there?

Starting The Computer In Safe Mode;
Free Online Encyclopedia

When our users are on the server and running Firefox, everything runs fine, but then it freezes randomly and the program has to be killed.

This is not of my league, but unplug the power for a 10 count to re-boot. and check for program updates.

I've called the big guys to help you. Good luck.

"Stopped interacting with windows" sounds like a "not responding" freeze or hang rather than a typical crash due to a memory violation, device driver fault, or out-of-memory condition. (Unfortunately, freezes do not generate a Firefox crash report.)

We do have a support article on troubleshooting freezes: Firefox hangs or is not responding - How to fix.

Since Flash can cause this problem and it is used pervasively through the web, I suggest the following to minimize potential issues with Flash during your troubleshooting:

(1) To avoid unnecessary pain on sites where Flash is not actually essential, try setting Flash to Click-to-Play ("Ask to Activate"). This will delay Flash from starting on a page until you approve it.

To set "Ask to Activate", open the Add-ons page using either:

• Ctrl+Shift+a
• "3-bar" menu button (or Tools menu) > Add-ons

In the left column, click Plugins. Look for "Shockwave Flash" and change "Always Activate" to "Ask to Activate".

With this setting, when you visit a site that wants to use Flash, you should see a notification icon in the address bar and usually (but not always) one of the following: a link in a dark gray rectangle in the page or an infobar sliding down between the toolbar area and the page.

The plugin notification icon in the address bar typically looks like a small, dark gray Lego block. (If it's red, Flash needs updating.)

The delay in activating Flash can help distinguish between problems caused on initial page load, styling, and script activation vs. loading/running Flash.

If you see a good reason to use Flash, and the site looks trustworthy, you can go ahead and click the notification icon in the address bar to allow Flash. You can trust the site for the time being or permanently.

But some pages use Flash only for tracking or playing ads, so if you don't see an immediate need for Flash, feel free to ignore the notification! It will just sit there in case you want to use it later.

(2) A common cause of unresponsive script errors on Windows Vista and higher is the protected mode feature of the Flash player plugin. That feature has security benefits, but seems to have serious compatibility issues on some systems. You can disable it using the Add-ons page. Either:

• Ctrl+Shift+a
• "3-bar" menu button (or Tools menu) > Add-ons

In the left column, click Plugins. On the right side, find "Shockwave Flash" and click the More link. Then uncheck the box for "Enable Adobe Flash protected mode" and try that for a day to see whether it helps.