Mozilla changes policy on certificates
Mozilla has announced that after June 30th, their software will no longer accept digital certificates that are signed using the MD5 hash algorithm for certain certification authorities (CAs). Vulnerabilities in MD5 can be exploited by attackers who then create fraudulent certificates. These flaws have been known for many years, and US-CERT declared MD5 unsuitable for further use some time ago.
You can read more about it here: