This has me stumped.

I bought a P4 2.4mhz, 256mb PC with XP Pro from an auction. It has a power button on the back and a reset button on hte front.

It works fine except for one thing. If I close down windows from the start button the computer turns off and won't turn back on. It goes completely dead and the only way to get it back on is to remove the lithium battery.

I am stuck having to use the restart option instead of the turn off option and when windows starts kicking back in I switch it off on the switch at the back.

Why oh why does it do this.

:-( Please, please please help.

Very strange.

Is it a standard looking case ? I can't see any reason why there isnt a power button on the front of the case.
You say there is a power button on the back of the machine. Is this the one on the power supply. (big black switch) with I and O on it.

Just curious, but lithium battery???

It's the BIOS battery my friend (sits on the motherboard) :smile:

[size=12px]The switch on the back is a I / O switch.

Although the button on the front appears only to be a reset button, could it be that it it is connected to the board incorrectly.

I can't understand why using the turn off option from the windows start button just kills the computer dead.

Why does removing the Bios Battery enable the PC to be restarted.

Is every one as stumped as me? [/size]

Well, it certainly seems to be linked to the power settings somehow.

Do you have a photo of your case? (attach it here)
Have you checked the power switch header on the motherboard?
Turn OFF all the power saving settings in the BIOS.

OK that makes a bit of sense.
You see the power supply button (Black one with I and O) is used to kill power to the motherboard completely.
When you Shut Down the computer from Windows it turns off but the motherboard is still supplied with 5 volts, called VSB for "standby voltage" even when it is officially "off", this is so that the power button will work.

Strange that removing the Bios battery helps boot the pc up but then again if you were to pull the power cord out the pack of the PC and plug it back in, then the PC will probably start up.

Right back to the problem. There must be a power button on the front of the machine somewhere, otherwise if you can't find one then it might be a plan to re-direct the Reset button so that you can use it as the power button.
But firstly if you could do as Hengis says and try send us a photo of the front of your PC.