After reading just about every solution regarding the problem of shutting down my PC ( a NUC) I have discovered the cause.
To set up the NUC and install programs I had it connected to my normal monitor and keyboard using a KVMP switch made by Aten.
Windows 7 was taking about 5 minutes to shut down and when it did would restart.
Disconnecting from the KVMP and it shuts down almost instantly and doesn't restart.
I have no idea why.