I am unable to open my yahoo e-mail. The requested URL /dc/launch was not found on this server. Apache/2.2.9 (Debian) PHP/5.2.6-1+lenny9 with Suhosin-Patch Server at us.mg4.mail.yahoo.com Port 80
I started having this problem after I downloaded Skype and made a call. I deleted Skype from my computer, then removed and reinstalled Firefox.
If you have Panda Cloud Antivirus installed, please see this thread: https://support.mozilla.com/en-US/questions/798059
Otherwise, follow co-rel's instructions in this one: https://support.mozilla.com/en-US/questions/784695