EC2 Windows: Certificate for local system with Thumbprint ... is about to expire or already expired

I regularly see this error in the Windows Error Log on one of my EC2 instances:

Certificate for local system with Thumbprint aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa is about to expire or already expired.

It appears EC2 uses a self-signed certificate to communicate with an Active Directory service somewhere on the EC2 network. It uses the certificate above to communicate with this, and tries to auto-renew periodically. It appears this mechanism has failed.

1. What problems can arise from this?

2. How do I fix this?

I attempted to follow the instructions here: http://technet.microsoft.com/en-us/library/cc774595(WS.10).aspx

But the certificate is not found - the Thumbprint is either an MD5 or more typically SHA1 hash. I searched for both criteria in mmc/Certificates and none were found.

How do I resolve this, and how problematic is it?