error after replace OWA certificate.

Hi,

my exchange server certificate expired, and I replace it with a new Digicert certificate.  After importing the certificate users report that when they access OWA using Chrome and Firefox, they see the RED X on the https, and the OWA URL changed to below:

"https://webmail.contoso.org/owa/auth/logon.aspx?replaceCurrent=1&url=https%3a%2f%2fwebmail.nflc.org%2fowa%2f"

Users report that they can logon and read email without any problems.

my environment:

Windows 2012 AD.

Exchange 2010

Thanks in advance.