I don't think anyone is going to be able to answer this without more information.
A few tools that will help you figure this out:
Sysinternals Process Monitor -> Options -> Enable Boot Logging
Reboot. Now you can evaluate that resulting ProcMon file, looking at the timestamps and looking for where the huge pause was. What was the system doing when that long wait started?
You can use Xperf to do a detailed boot trace as well:
You can also enable verbose logging of Group Policy Processing:
Using these tools is probably the only way to begin to figure out what is causing this slow boot time.
Edit: Here is a fourth verbose logging method for you to look at: