Does this error at Group Policy Processing happen at startup (I mean, when you boot the machine)?
If so, It´s very probable that you have enabled "Spanning Tree Protocol" (STP) at the ethernet Port where your machine
is connected. If STP is enabled, it takes about 30seconds for the ethernet port for being operational and start forwarding traffic. While the port remains at the LEARNING STP protocol STATE, no traffic (except de BPDUs associated to STP) are forwarded. That causes that the DNS queries sent by this PC are blocked at the ethernet switch.
* Disable STP at the ethernet port (if you may assure that no switch will be plugged in to that port in the future) or
* Enable STP FastStart. Even with this solution, where the transition to FORWARDING state happens in 3-4seconds instead of 30, current machines boot so quickly that first DNS queries are sent when the port is alredy at the LEARNING state)