Please check the processor heat sink and remove the dust. This may be due to overheating. Pl remove all the plugs before doing any physical repair.
Do you mean power off or complete shut down. If the power is off, then enter key would resume your normal screen you were last on.
If you meant, shutting auto, then it is virus doing and Boggins suggestion would do the remedy for you.
HI, Boggins, what are all those colours denote in Process explorer and not in the virus total. some shown as red , some shown as pink etc. How to identify the process that gives the problem from PExplorer. This i want to know . Thanks