My PC keeps restarting.

[NoLifeKing]

hi
im using windows 8.1 and every time i lock my computer it restarts or logs me out after a few minutes.im not sure which one it is cuz i haven't actually seen it restart. i just leave for 30 mins and when i come back and enter my password all the programs and applications have been closed and and programs like skype start up
any ideas?

 

[yumri]

windows 8.1 does that thing when it locks itself to which only the metro apps come up again and all the others dont how to change this though i do not know but i do know that it is normal for it to do it.

 

[NoLifeKing]

windows 8.1 does that thing when it locks itself to which only the metro apps come up again and all the others dont how to change this though i do not know but i do know that it is normal for it to do it.

ok thanks