Intermittent authentication errors

[kgmcveigh]

Hi Folks,

We are on 10.1 FP2 running on a 2008 R2 VM. In the past week users have been getting intermittent authentication errors when logging into contributor via the web. We are configured to use our Active Directory for authentication. It just seems to come and go.
The event log on the server has some group policy errors in there that I haven't seen before -

"The processing of Group Policy failed. Windows could not authenticate to the Active Directory service on a domain controller. (LDAP Bind function call failed). Look in the details tab for error code and description."
AND
"The processing of Group Policy failed. Windows attempted to retrieve new Group Policy settings for this user or computer. Look in the details tab for error code and description. Windows will automatically retry this operation at the next refresh cycle. Computers joined to the domain must have proper name resolution and network connectivity to a domain controller for discovery of new Group Policy objects and settings. An event will be logged when Group Policy is successful."

Also cognos logs showing similar stuff -
"cmAuthenticateFailed CM-CAM-4005 Unable to authenticate. Check your security directory server connection and confirm the credentials entered at login."
"The encryption type requested is not supported by the KDC"

Our systems / network guys are looking into this now but they're not reporting any AD / LDAP issues that they know of - but it seems obvious that the server is having problems authenticating to the AD
Has anybody seen this before or can point me in the right direction?
thanks,
Kieran.