I do see this scenario as a potential black screen, but don't think we are running in to this, however I certainly will double check our DHCP scope and DNS scavenging.
As we dig more in to our black screen problem we are leaning towards networking or storage. If we log in to the VM with a black screen after the black screen has occurred we see a user profile half-merged (not entire content is copied to the vm from the server share)
So the other suggestion to verify the port settings on the switch is a good place to restart our investigation and perhaps dig in to the storage logs to see if there are any resets on the storage controller.
Thank you!