Help! What's wrong with my laptop?

[Tarka]

Just tried to use laptop - it's totally dead - you can't do a restart with the power button (which looks on, but screen is black). Any ideas? Its only 4 months old...Thanks in advance.

Have you tried removing all power source ie the charging lead and the battery,this will force a shut down,not ideal but may your only option.Does it start after trying this.

What make and model is it?

Thanks, will try that - it's a Compaq CQ58.

Chanatan, that sems to have worked, thank you! Any ideas on what could have caused this?

I had an Hp pavillion that kept doing it and that turned out to be related to the fan,but having said that it could be one of a number of things.