Hyperv Dashboard

Hi,
we have a problem that sometimes our Hyper-v dashboard appears with a list of hyper-v machines, and sometimes it does not.
We use the Hyper-v with a lot of machines on it to manage all different vpn's we have to customers.
These machines are shutdown every night so we need the dashboard to be able to start these machines...

Is there somewhere a log of other where i can see why it sometimes does not work, because i don't seem to find any logic in when it works and when not...