Random Computer Resets?

[schut]

My grandmother was recently having a problem with her computer,
It is about a 5-year old IBM NetVista with a 1ghz Celeron

She wanted a reinstall of Windows, which i did, but now i cannot install any updates such as SP2 because computer just resets unexpectedly every few minutes.

Can anyone give me any ideas of what to look at?

thanks,

 

[nuke]

Click Start, and then click Control Panel.
Click Switch to Classic View if Control Panel is not already in Classic View
Double-click System, click the Advanced tab, and then under Startup and Recovery, click Settings.
Under System failure, click to clear the Automatically restart check box.
Click OK twice.

 

[schut]

I don't think that's exactly it, though.. because I thought maybe it didnt like WinXP, so i tried installing Windows 2000, and the same kind of thing happened. While it was installing the network components, the thing resets, and it did that 3 times in a row, during the part where it installs the network components.

thanks for the reply