And also thunderbird is not working, too. I open it but its not connecting...

Check the date and time and time zone in the clock on your computer: (double) click the clock icon on the Windows Taskbar.

Check out why the site is untrusted and click "Technical Details" to expand this section. If the certificate is not trusted because no issuer chain was provided (sec_error_unknown_issuer) then see if you can install this intermediate certificate from another source.

You can retrieve the certificate and check details like who issued certificates and expiration dates of certificates.

• Click the link at the bottom of the error page: "I Understand the Risks"

Let Firefox retrieve the certificate: "Add Exception" -> "Get Certificate".

• Click the "View..." button and inspect the certificate and check who is the issuer of the certificate.

You can see more Details like intermediate certificates that are used in the Details pane.

If "I Understand the Risks" is missing then this page may be opened in an (i)frame and in that case try the right-click context menu and use "This Frame: Open Frame in New Tab".

• Note that some firewalls monitor (secure) connections and that programs like Sendori or FiddlerRoot can intercept connections by linking in the LSP chain and send their own certificate instead of the website's certificate.
• Note that it is not recommended to add a permanent exception in cases like this, so only use it to inspect the certificate.

Thanks first of all for your respond.

"I Understand the Risks" missing. The only options is somethnig like "Get me out of here"...I opened it in a new Frame but its the same...

Regards

Are you going to your email through a page that redirects? If so, can you access this page directly: https://login.live.com/login.srf

If that doesn't let you view the certificate for live.com, have you created exceptions for any other sites recently? If so, we might be able to learn about whether your security software is a factor by checking the certificates for one of those sites. To do that:

Load the site, then click the padlock in the address bar, then the More Information button, then the View Certificate button. This should display a small window. What do you see in the "Issued by" section?