Hi Geoffrey, By looking at the scenario it looks like either there is a throughpur issue else your DC is running out of resources when all users are logging in. I would first like to look at the configuration of the Hyper-V host and then of the VM that is running as the DC. I would also like to know about how network is setup in Hyper-V. Have we installed Integrated services? Please give more details. Thanks Please remember to use “Mark as Answer” or "vote as helpful" on the posts that help you.