HP pavillion desktop won't turn on...

[Cyndicate13]

This past weekend my moms pavillion desktop wouldn't turn on. It's about 4 years old.
The power button usually glows orange when off and turns blue when on, but it's not illuminated now.
The psu has a green led on the back, it's off. When I unplug the psu cord and plug it back in, it goes on, then goes out when I push the power button. I then have to unplug the cord again, hold the power button for a few seconds to make the light flicker, then the light goes on when I plug it back in but same result.
I'm wondering if it's a power supply issue (dead or dying)?

Any thoughts?

[Bama19642]

That is probably the best place to begin. Find a PSU calculator and buy an Antec that has 100 watts more than the calculator estimates. I say Antec because they usually have 350-500 watt units at a decent price. Don't get one for under $40 regardless of brand. Cheap power supplies are the worst place to save money.