My interpretation --

You have at least two problems, one of which is defective hardware and
another is related to Windows' installation. If you could get into
Safe Mode and stay there consistently, this might be something you
could fix by finding more appropriate device drivers. However, you say
that Safe Mode is unstable. Furthermore, you say you get different
error messages on different occasions. Such behavior can only come
from hardware, as software would d  the same things each time you
start the computer. You need to get reliable hardware before you can
do anything with software.

Bill Starbuck (MVP)