If your Windows VPS is randomly shutting down every hour or so this is normally caused by a Windows activation issue. First, check if your Windows OS has a valid license key and is currently activated. If not please follow the below instructions, if a license key has been entered and is valid submit a support ticket via the client area for further assistance.
To fix this problem simply :
Open CMD on your VPS
Type in > slmgr /rearm
Once it has finished, it will ask you to restart, do so, then your good to go.