Please refer the below article for the solution. Also, please backup the windows settings as I cannot confirm that GP will work after this as I haven't tested this. https://support.microsoft.com/en-us/kb/2797356 Let us know how it goes. Thanks!
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Please let me know if this helps: 1) Instead of creating a separate cert to use as a forward untrust, try using the existing cert as both, forward trust and forward untrust. 2) Disable blocking of any untrusted issuers in the certificate profile or try disabling the cert profile altogether.
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