This is an issue that historically I have found often with wireless network connections, but very rarely with wired connections. This has always been easily resolved by simply pushing the pretty standard GPO found below:

Computer Configuration\Policies\Administrative Templates\System\Logon

Always wait for the network at computer startup and logon

Naturally I stumbled upon a case where this was not the case. I pushed the GPO and even changed the local GPO to no success (the main indicator being an error in the event log saying it couldn’t contact DC during logon). One Google search later I found the answer (here). Set the following local GPO:

Computer Configuration\Administrative Templates\System\Group Policy

Startup policy processing wait time = 120

You can play with the wait time numbers, but 2 minutes worked for me.  As one would expect this does slow the boot time significantly (by two minutes, who would have thought), but it will get you up and running.