Clear the cache and the cookies from sites 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 > Cookies: "Show Cookies"

Try rename the cert8.db file in the Firefox profile folder to cert8.db.old or delete the cert8.db file to remove intermediate certificates that Firefox has stored.

If that helped to solve the problem then you can remove the renamed cert8.db.old file.
Otherwise you can rename (or copy) the cert8.db.old file to cert8.db to restore the previous intermediate certificates.
Firefox will automatically store intermediate certificates when you visit websites that send such a certificate.

If that didn't help then remove or rename secmod.db (secmod.db.old) as well.

Thank you for your reply but it seems like the problem is not something related to certificates or certs db.

Today when i was trying to send an email, google page appeared with a 404 error while both address and status bar show *.mail.yahoo.com but the appeared page belongs to google !

I've attached a screen shot.

I've been using firefox since 2004 and never experienced such problem !

Thank you, Max

Are you using a bookmark to go to this page?

If you do then try to reach this page by navigating to it from the main k page.

Clear the cache and the cookies from sites 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 > Cookies: "Show Cookies"

Alarming!

If you right-click the not-found-on-Google-cache page and select View Page Info, does the URL match the address bar?