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Using the tool is detailed here - http://blogs.technet.com/b/askperf/archive/2012/02/03/wmidiag-2-1-is-here.aspx
For Windows Core servers, ensure you allow the firewall connections as per - http://blogs.technet.com/b/brad_rutkowski/archive/2007/10/22/unable-to-remotely-manage-a-server-core-machine-mmc-wmi-device-manager.aspx
AntiVirus
Some antivirus programs have been known to disable DCOM and remote WMI. You might check the settings of your antivirus program and disable them for testing.
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