Hi there, I'm having an issue validating a 2 node Windows 2008 R2 cluster, however I don't actually think it is anything to do with the validation tool. From the errors I'm getting it very much looks to be a permissions issue. If I add these same two nodes to a Windows 2003 domain, or a Windows 2008 R2 domain that has been upgraded from a Windows 2003 domain I have no issues and the validation tool comes up green across the board. It is only on a vanilla install of AD on a Windows 2008 R2 environment that I am getting these errors which is making me think this issue might be being caused by AD. The errors come up during the "List All Disks" with the following error; An error occurred while executing the test. Storage cannot be validated at this time. Node 'prd-msc1n2.home.local' could not be initialized for validation testing. Possible causes for this are another validation test is being ran from another management client, or a previous validation test was unexpectedly terminated. If a previous validation test was unexpectedly terminated the best corrective action is to reboot the node and try again. Access is denied Then again on the "Validate Cluster Network Configuration" and"Validate IP Configuration" tests with this error; An error occurred while executing the test. There was an error initializing the network tests. There was an error creating the server side agent (CPrepSrv). Creating an instance of the COM component with CLSID {E1568352-586D-43E4-933F-8E6DC4DE317A} from the IClassFactory failed due to the following error: 80070005. All tests are being run with domain admin privs and running the validation test on each node just on themselves works fine, it is only when the test includes a remote node that these errors occur. At first I thought it may have been something to do with the default group policies (domain and domain controller) between 2008 R2 Vs 2008 R2 upgraded from 2003 as I compared them and did notice differences, however there was no difference in my cluster validation results after having imported the policies across. I've also tried changing the default impersonation level in COM from identify to impersonate on the DC, as well as removing the cluster nodes from the domain and adding them again. Just wondering if anyone has any more precise idea on what the above errors are referring to exactly? I've examined the Windows event logs which don't seem to contain any information of relevance to the above errors. Any suggestions on what I can try next?