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Note - All commands below should be entered into an elevated command prompt. To do this click Start -> All Programs -> Accessories -> Command Prompt, right click then "Run as administrator".
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DCOM
Run the DCOM utility and verify (or set) the below attributes. Start -> Run, Enter DCOMCNFG and press OK. This will open the DCOMCNFG window.
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Close the DCOMCNFG window and restart.
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UAC
If you are getting an Access Denied scan error it might be UAC blocking inbound requests on the remote device. If the remote computer you are trying to query is in a workgroup (or not joined to a domain), UAC prevents remote queries by default, even if the account being used is in the Administrators group. Completely disabling UAC on the remote device allows you to get around this, but it is preferable to disable the subcomponent of UAC instead. You can do this by adding or editing this registry key on the remote device you are scanning and setting it's value to 1:
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The above changes will require a reboot to take effect.
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WMI
Windows WMI (Windows Management Interface) is use by the audit script for most of it's information retrieval. WMI can (at times) become corrupted. Microsoft have released a tool to enable you to check for this corruption.
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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
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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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