‘web site won't let me sign in on fire fox but will on chrome. error message says "something went Wrong" and reloads login page’

You can search the forums here for the site name if it's more common, or use the built in functionality to "Report Broken Site" from the browser menu to capture some more logs.

I have tried clearing cookies and turned off site protection. no help

Try restarting into Troubleshoot Mode from Help menu to figure out if that might be caused by an addon — security appliances over at big site operators do not like these tampering with their content.