azure vm shutdown randomly

after deploying new VM B series, the VM going shutdown with deallocating status randomly "no automatic shutdown enabled "
from azure logs it same to be the VM shutdown by authorized user
"The shutdown was triggered by an authorized user or process from either the Azure portal or from Azure Resource Manager interfaces. Your VM remained in this state until user action was taken to restart it."
from the VM event viewer it say the
The process C:\Windows\system32\svchost.exe (servername) has initiated the shutdown of computer servername on behalf of user NT AUTHORITY\SYSTEM for the following reason: Other (Planned
any idea what the root cause for this issue!