The American Megatrends message appears

Good morning,
I've had a problem turning on my computer for two weeks.

An American Megatrends message's appeared(here the picture):

I clicked F1 to enter the BIOS,

but not knowing what to do, I have chosen the option "exit without saving", after that the (blue) recovery screen appeared. I tried to fix the problem from there.

I waited 1 hour for repair and I thought the computer had crashed. So I forcibly turned everything off. I know I was not supposed to do that move !!!
However, the computer restarted/turned on without any messages. But five days later, American Megatrends message is appeared again! and again and again!

I did the same thing again, I clicked F1 (as requested) and then "exit without saving" (from the BIOS). The computer did not give me the blue screen, it just turned on normally.
Now, everytime I must enter in my desktop and stuff like that, I must do that same process : Entering BIOS and exit without save.

But it looks obvious, there is an unsolved problem here.
What should I do to solve?I need some advices.
I read about changing "battery cmos", but it seems different people have conflicting opinions about this.