tlarue said

Hi, We have a server and have noticed that one of our internal websites will no longer open on this server in Firefox 4.0.3. It will open with no problems at all in Chrome. It will also not open in IE9. I have no idea why this is happening. The error message in Firefox is ""Bad Request - Invalid Hostname \\\\ HTTP Error 400. The request hostname is invalid."" I have cleared cache, cookies and also deleted and re-installed Firefox on this server but site still doesn't work. Other internal/external sites open in Firefox with no problem. And have done some research online without success.

Forgot to mention that this website that will not open in Firefox on the server opens with no problem in Firefox on our PCs.

See if these help;

http://www.ehow.com/how_11385212_troubleshoot-reset-connection-firefox.html

https://support.mozilla.org/en-US/kb/server-not-found-connection-problem

https://support.mozilla.org/en-US/kb/firefox-cant-load-websites-other-browsers-can

https://support.mozilla.org/en-US/kb/secure-connection-failed-error-message

https://support.mozilla.org/en-US/kb/connection-untrusted-error-message

http://kb.mozillazine.org/Error_loading_websites

This Connection is Untrusted is sometimes caused because the computer system clock is wrong. Check the time / date / time zone settings.

Separate Issue; Your System Details shows;

Installed Plug-ins

Adobe PDF Plug-In For Firefox and Netscape 11.0.10 Adobe PDF Plug-In For Firefox and Netscape 10.1.13
Having more than one version of a program may cause issues. You must remove the older programs. Then get the current full installer.