Hmm...I guess it could be a W7 bug. I just didn't think other W7 users had that CIS bug. Well, W7 is not fully supported so...
Anyway, one more thing (yeah I know you said "everything has been tried" but still...

): you could try changing RunDLL32's policies/permissions in CIS to Windows System Application.
Go to the Defense+ tab > Advanced > Computer Security Policy > Find and double-click the RunDLL32 entry > Change the predefined policy to Windows System Application > Apply.
If this doesn't help, or if RunDLL32 was already a Windows System Application...then I'm afraid I can't help you any.
I looked at your suggestion.
There is no"Windows System Application"
The two alternatives are"Use a Predifined Policy" or "Use Custom Policy.
At the moment it is set to "Custom Policy".
Regards