Game freeze!

[countess]

First post, this might be the wrong section >_>

So I bought a new computer about a month ago because my old one just died one day and refused to start up.

We got it so my mum could do her work and I could play games on it. I'm a big gamer so it was important to get a good PC for me.

We bought a Packard Bell computer with XP on it and for about two weeks it was absolutely fine, it would run my games with no problems.

However over the past couple of weeks it has developed this irritating little habit of freezing if I leave a game idling for too long or sometimes just randomly freezing up while I'm playing. The thing is, at first I thought it was just game lag. But now I've worked out that it's not lag because the computer creaks as it's trying to work out the lag then it's fine.

It's not an issue with the game itself.

What generally happens is that it will just freeze the picture but the sounds will continue. Sometimes though the sound freezes too.

It's incredibly annoying.

I was recommended to check what other programs were running at the same time, but none are. I ran msconfig and shut down all unnecessaries at startup too. It's not a RAM issue because I've checked that repeatedly.

I'd like an answer to this in words of one syllable, I'm not good with computers and need the simplest solution possible.

I'm running on the latest Athlon processor by the way and an NVidia graphics card.

It's made more annoying by the fact that this is a brand new computer!

Any help much appreciated. Thanks!