Why would a hard drive do this?

[Rubberhead]

Hi there, I have a fairly new 160gb hard drive, and it prevents my
comp from booting. I woke up the other morning, and couldnt switch
my comp on, the fans would power up, then off again, but the mother
board thinks its still on, the power light stays on until I hold the power
switch for 4secs. No beeps, just a brief burst of power then nothing
I got the machine to boot the other day by tapping it and kind of coaxing it
to come on.
I have since found out what it is, and its my 160gb hard drive (secondary)
If its plugged in it prevents the machine from booting.
I dont think its the psu connectors as Ive tried all that will fit in many configurations, connecting only primary boots no probs,
connecting only secondary using same power connector doesnt boot
Bear in mind this machine has been stable for months, and all of a sudden this happened.
Any tips, suggestions, anyone had this happen as well, much appreciated
Many Thanks
Gary

 

[Rubberhead]

Its absolutely pouring it down atm, so I havent, Im having a bit of
bother getting in touch with some peeps as well, its just not my day.
Im just wondering, has a drive died like this on anyone else before? In my
experience a dead or dying drive tells you so. Even if a drive has totally
failed before, the mobo would post to tell you so, Ive never had a machine
just 'switch off' like this before.

 

[Rubberhead]

Hahaha, how weird you say that, I have just returned from my friends house.
We put the hard drive in an external usb case, and it worked fine,
he's lent me the case, and I am now listening to music from it.
This is the weirdest problem I have ever come across, it just defies logic,
and leaves me pondering my next move.... new hard drive?

But why would one hard drive work fine, then another stop the machine from
posting, using the same power cable, 100% of the time, it doesnt feel like a
loose connection.

Argh, I'm gonna have a beer, and back my files up, cheers all!

Gary