Novell ZENworks Configuration Management 11.2
Agents marking primary bad or busy, slow login/slow refresh.
From agent zmd-messages.log:
[DEBUG] [02/26/2014 08:54:12.502]  [ZenworksWindowsService]   [ContentManager]  [GetContentInfo Error: System.Net.WebException: The operation has timed out
From services-messages.log on primary (repeated over and over):
[DEBUG] [2/26/14 11:45:10 AM]  [Content Web Service]   [getContentInfoEx - Not sending the content information for the contentID : 79ddff73880ddfaee432eadb3c694427, belonging to : "some bundle", since the filechecksum in this content is null i.e. content is not yet available for download]  
If the content checksum is invalid, either devices assigned to this bundle or primaries/satellites trying to replicate this bundle will cause the primary to get slow and unresponsive and marked bad. Delete the bundle noted in the log above, or remove assignments and remove include to sync to other primaries and satellites until the content can be re-uploaded and confirmed to not have bad checksum.
Select * from zcontent where aliasedcontentuid is null and zuid=[guid from log] ex: 0x79ddff73880ddfaee432eadb3c694427 to confirm null filechecksum or content checksum. NOTE: Aliased content will have null checksums so be cautious to investigate only those having no alias.