You receive an error (or similar), WMI invalid class, when running a WMI scan or you receive the error as part of a scan that does not include a WMI scanner.
In either of the cases above, a request was made for an unknown WMI class.
WMI Scan Error:
If the error occurred when running a WMI scan, this indicates an issue with the selected class in the query is in some way, invalid, usually due to a spelling error. You can test this by running the same query in WMI Explorer (Options > Scan Profiles > [WMI scan profile] > Edit > [WMI scanner] > Edit > Launch WMI Explorer). Once you have concluded the test and corrected the problem with the class, run the WMI scanner again. If the error continues, please see the Other Error section below.
For additional information regarding the WMI Scanner, please see the Inventory WMI Scanner: Usage & Examples KB.
The most common cause of this error is missing data in the WMI database. It may also be a bug in the PDQ.com software making a request for information that doesn't exist on a particular version of Windows.
See the WMI Diagnostics KB for information on how to rebuild the WMI database.