http://gefest.rads-doi.org/index.php/login I got to the login page with no problem.

This site uses the SHA-1 certificate; use certificates with the signature algorithm, using a stronger hash than the SHA-1. [More]

With the newest Firefox, some Security Certificates have been disabled because of issues with new mal-ware. Can you check with the site on what Security Certificates they are using? (SSL and TSL encryption protocols)

https://developer.mozilla.org/en-US/Firefox/Releases/37/Site_Compatibility#Security

https://blog.mozilla.org/security/2014/09/23/phasing-out-certificates-with-sha-1-based-signature-algorithms/

This is merely a notification meant for the website administrator that they should update their server software and this shouldn't affect the functionality. If there are problems then something else is wrong.

This issue can be caused by corrupted cookies or cookies that are blocked.

• check the permissions on the about:permissions page and in "Tools > Page Info > Permissions"
• https://support.mozilla.org/kb/fix-login-issues-on-websites-require-passwords

Clear the cache and remove cookies only from websites that cause problems.

"Clear the Cache":

• Firefox/Tools > Options > Advanced > Network > Cached Web Content: "Clear Now"

"Remove Cookies" from sites causing problems:

• Firefox/Tools > Options > Privacy > "Use custom settings for history" > Cookies: "Show Cookies"

Start Firefox in Safe Mode to check if one of the extensions (Firefox menu button/Tools > Add-ons > Extensions) or if hardware acceleration is causing the problem.

• Switch to the DEFAULT theme: Firefox menu button/Tools > Add-ons > Appearance
• Do NOT click the Reset button on the Safe Mode start window

• https://support.mozilla.org/kb/Safe+Mode
• https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes