Dell Vostro 230 Shuts down and powers up on its own. Also DVD Burner drive does not show up on my computer.

Hi,

I have a Dell Vostro 230 that shipped with Windows 7.  Some time ago, I came home to see it up and running although I had not left it turned on.  This happened a couple of times and I began to leave it unplugged.  When I needed to use it, it would work for random amounts of time then shut down.  I would try to start it but it would start up and then immediately shut down.  Over and over.

I recently upgraded to Windows 10 hoping that this might solve this problem but it did not.  Additionally, now my DVD R/W drive does not show up on my computer.

I have checked it for dust but it was clean inside the case.  I have removed, swapped the memory.  I have checked the power supply unit and the connections with a PSU tester.  All have checked fine.

I am not sure what may be happening?  Can anyone help?