Digicert Intermediate Certificate suddenly failing...

Hi all!

We have an install base of a few hundred Macs ranging from 10.7 to 10.10. Suddenly, several of the machines seem to be missing the Digicert SHA2 Secure Server CA intermediate certificate. We noticed the problem after several users reported warnings with our VPN appliance, which uses Digicert certs for ID.

Reinstalling the certificate from Digicert's site clears up the issue, but I'm trying to root cause the problem. The issue appears to happen only on 10.9.x, and seems to happen before OR after the 2015.004 security patch. The patch does not resolve the problem.

I know folks have reported similar issues with Verisign certs and the 2015.004 update.

Any ideas? I've only seen this on a very small fraction of systems, so I'm not super concerned, but it is annoying...