iMac keeps shutting down

Hello,

I recently got an iMac that has never been used, but is 18 months old and out of warranty.

It was ok for a couple of days, but now just shuts down after a short while of being switched on. It does this repeatedly.

Is there anything I can try at home before getting it looked at?

Thanks

A never used 18-month old iMac? What are the specs? OS version? and unless you got this VERY cheap, why would you purchase (assuming you did) a nearly 2 year old iMac?

Regards

Yes, I know it's a bit odd. I got it through work - it had never been used - long story.

It is OSX running leopard.

Take it to the nearest authorised Apple repair centre.