I get error "1065" from Group Policy when trying to run GPUpdate, and Group Policy is specifying that it cannot process the WMI query. I can successfully run some queries manually, but WMIDiag returned a number of missing objects in the CIMV2 namespace. I've tried reregistering MOFs, salvaging the WMI repository, resetting the WMI repository, and even manually rebuilding it (all as detailed on Technet,) but none of these actions have corrected the issue.
Another point of interest is that, if I run WMIDiag with the writeinrepository option, I get a message back about "insufficient disk space" even though there is plenty of space on the disk: I figured this was due to the repository hitting its quota, but it persists even after the above actions.