As you have seen from the many suggestions, this is a difficult problem to 
diagnose.  I am making my suggestion here because of  the "click" that you 
describe.

I had a similar problem that I traced back to either the motherboard or the 
power supply.  The power supply checked out good, using a simple tester, so 
I replaced the motherboard.  Still problems.  Then I replaced the power 
supply and all cleared up.

This happened to me twice (mine and my wife's computers) within a period of 
less than two years!  My power supplies were expensive PC Power and Cooling 
ones that cost $200 each about eight years ago.  Both times they tested 
"good."  The first time with the paper clip test (their web site describes 
this) and the second time using a cheap tester, which is for all practical 
purposes the paper clip test.

The symptoms of the most recent failures were erratic behaviour for a few 
days, with the computer being able to stay on for less and less time. 
Finally, it got to be very much like your symptoms, where it got 
tantalizingly into the boot process then "clicked" back to a reboot.

Since it can get expensive swapping out parts (motherboards, power supplies, 
hard disk drives, memory, etc.), you may need the help of a friend with a pc 
who will be willing to loan you his power supply.  You just need to connect 
the basic things: motherboard, hdd (it needs an electrical load, plus you 
can see if it will load the operating system), and maybe the video card. 
After my first failure, I bought a power supply from Compusa for about $30 
while I waited for my new one to arrive.  So the second time I had a spare 
one. :)

There are several other things to consider.  The first, unlikely but 
possible, is overheating.  If you have a can of compressed air, you can blow 
out the insides of your computer to clean off all the excess dust.  However, 
you crash pretty early in the boot process for overheating from dust to be 
the cause.  A remote problem is that your cmos battery has gone weak and 
your bios are not set correctly.  (This doesn't sound like it matches your 
symptoms, but you never know.) If I am doing extensive work on an old 
computer, I usually put in a new battery.  Most of the ones used today are 
CR2022 and are available at Wally's for about two dollars - pretty cheap 
insurance, and they are going to go bad after a few years anyway.

HTH

Dean Kukral


----- Original Message ----- 
From: "Stephen R Stanfield" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Sunday, August 13, 2006 12:18 PM
Subject: [PCBUILD] System won't boot


Hello All;
When I turn on pc it goes thru boot-up process until Win xp startup page
comes on, then makes 'click' noise and goes thru boot-up page and
repeats process over again.  Tried to go into safe mode, but same event
occurs.  Any ideas what might be going on?  i am using my laptop now,
but need my pc also. AMD  Athlon 1.7ghz, 1 Gb ram 80 gig hd, Win xp home
sp-2,
thanx,
stephen r stanfield

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