Stop during boot

Hi,

my system stops booting (from time to time). It starts, than the cursor is frozen in the upper left corner, after a minute or so it starts blinking - ant that's it.

I do reboot in safe mode and refresh the grub2 by typing

sudo grub2-mkconfig -o /boot/efi/EFI/redhat/grub.cfg

After that I can reboot in the standard kernel.

Unfortunately I do not see the systematic, why it breaks sometimes and sometimes it starts up smoothly.

Any fix or experience appreciated! Have a good start in the week!
Claus