Question : Problem: Why does my pc turn itself off immediately after I try to power-up?

I have a ten-year-old system, which, by and large, has been very good over the years. It's still behaving itself really quite well, but for some reason it has suddenly started turning itself off immediately I press the power switch to boot-up each morning*. It keeps going, as it were, at the second, third or fourth attempt, but obviously something is not quite right.

Any suggestions much appreciated, but, *please*, in simple language. I'm not a techie by any stretch.

Many thanks

Neil C

*I've never really known the ideal, if there is one, with regard to leaving on 24/7, turning off each night, 'stand-bys' and 'turn-offs'; I've always turned off at night and my settings (W98, by the way) are screensaver after 10', turn off monitor after 15' and hard disks (I have two; the original small disk and a much larger, more recently installed, D disk) after 20'. Systems is on never. Any advice on this, too, much appreciated

Answer : Problem: Why does my pc turn itself off immediately after I try to power-up?

More than likely if you look at the motherboard you will find bad capacitors. This is a classic example of this type of issue, and requires either the capacitors(not really worth it)  or the motherboard to be replaced . Here are some pictures of what to look for.
http://www.badcaps.net/ident/ just clcik on the pistures to get a closer look.