Firefox shouldn't overwrite system files, critical or otherwise. Did support say what files Firefox overwrites?

Windows include a program to repair damaged system files which you can run to see whether that makes a difference: Use the System File Checker tool to repair missing or corrupted system files. I think that's worth running to test this theory.

Firefox will modify some registry settings to make itself the default browser if you approve that. If the Tyler software doesn't work when Firefox is the default browser, you can have IE make itself the default browser as a workaround.

Is the Tyler software a browser-based application? In that case, here are some other troubleshooting suggestions:

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:

orange Firefox 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"
• Alt+t (open the classic Tools menu) > Page Info > Security > "View Cookies"

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

Then try reloading the page. Does that help?

Many users have recently become more aware of privacy and either made changes to their cookie settings or installed extensions that stop some information from reaching websites. While this reduces tracking, it also can cause some site functions to break.

As a test, try using the application in Firefox's Safe Mode in a Private Browsing window. This will help bypass restrictive cookie settings, as well as other filtering behaviors of extensions, to see whether those are a factor.

You can restart Firefox in Safe Mode using

Help > Restart with Add-ons Disabled

In the small dialog that should appear, click "Start in Safe Mode" (not Reset)

Then open a private browsing window using either:

• Ctrl+Shift+p
• File menu > New Private Window
• orange Firefox button > New Private Window

In that window, try Tyler. Any difference?

Thank you for your replies. What was happening was the experts at Tyler insisted our problem was Mozilla Firefox. They claimed Tyler would not work on IE if Firefox was installed. They suggested I reimage all computers without Firefox. That was not an option. Well what I found out was that IE 11 is being pushed out and is not compatible with Tyler so my teachers were getting this update unknown to them. IE 10 also has issues, but IE 8 and 9 work great with or without Firefox on the computer. Firefox is well like at our school.

Thanks for the update; hopefully other Tyler users will find this in web searches and benefit from your research.