Presario 6029 repair problem

Howdy: I've got a neighbors Compaq Presario here that just plain
refused to let me repair it. I put the Compaq Operating System CD
into the drive and go through the repair process just fine until it
gets to the "Installing Devices" window at about 34 minutes left and
it stalls there for about five minutes and then it re-boots and
starts all over again. And again. And again.

Using his monitor it would say that Compaq was going to sleep (LCD
screen) and on my monitor (CRT) it just re-boots. It did this before
I put in the repair CD also. It would get to a DOS window on boot up
that give the choice of Safe Mode or Starting in Normal Mode and a
couple of other choices, but no matter which one you picked it would
site there for about four or five minutes and then go to sleep
(using his monitor). Help! I'm at a loss to explain it. I was
thinking the power supply, but it is to predictable, not random
enough for that to be the likely reason?

Any more info that any one needs just let me know. I'll the be the
one sitting in the corner tearing his hair out!

Lowrent in TX