We are seeing the following in our Exchange 2010 cluster DAG:

The Cluster service is shutting down because quorum was lost. This could be due to the loss of network connectivity between some or all nodes in the cluster, or a fail-over of the witness disk.
Run the Validate a Configuration wizard to check your network configuration. If the condition persists, check for hardware or software errors related to the network adapter. Also check for failures in any other network components to which the node is connected such as hubs, switches, or bridges.

The cluster service stops and we lose the DAG completely.

I really don't want to re-install

Can anyone help?

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Also we see: Joiner tried to Create Security Context using Package='Kerberos' with Context Requirement ='67586' and Timeout ='30000' for the target = 'SERVERNAME'

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We have solved this by making sure all servers are up to date with the cluster patches and latest roll-ups and that they are all the same version. It is fixed using the remote data centre patches for the Windows Cluster and Exchange Server Services.

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