I am at my wit's end with these two machines. One is a Pentium 4 2.4G
on a ASUS P4B533-VM MOBO, the other an AMD Athlon 64 2.4G on a ASUS
K8V SE Deluxe MOBO. Both have 640G DDR. Both use the same mouse,
keyboard, and monitor through my KVM. Both are LAN'ed together via a
D-Link router. Both have 400W+ PSU's. Both have relatively new HDD's
as C (boot) drive.

I have had this problem before, and often I go several months before
it happens again, like now. In fact, it happens so often, that I have
to leave both towers open so as to make it easier for me to deal with
the problem.

I find that more often than not, when I boot-up either machine, it
either will not boot up at all or will boot up with a missing drive or
drives. Both machines are running with two HDDs and one DVD. If it
boots up and the missing drive is not the C boot drive, like say the
DVD drive, then I may not notice the missing drive right away, if at
all.

I have changed both IDE cabling to new ones, and it is still
happening. I have changed drive power connectors from the PSU's, by
adding Y-extenders.

Generally, I can jiggle (or re-seat) just the power connectors for the
problem drive(s), and the next re-boot will be correct, and stay that
way for a day or two.

I have not noticed loss of a drive or drives while running, but once
in a great while a machine will crash with a black screen or lose its
mouse/keyboard, so I guess it could be happening, so I can't be sure

I sure would like to try another course of action.

Since this happening on both of my side-by-side machines, I am
baffled.

Any ideas as to what I can try?
Thanks
Jethro