Computer has a mind of its own

[wduk2005]

Hi, my computer seems to always be doing something even when its just left, its making it run really really slow.
I've got windows task manager up and i leave it with nothing running and just watch the cpu usage one second it'll be at 5% the next junp up to 84% and just keep chnging. Also the little light that shows that its doing something is always flashing.
whats causing this and how can i stop it.
Its a lap top as well so prob not cheap and easy to change parts of it.
Thanks in advance to anyone who can help

[Llamatron]

Try downloading Security Task Manager.
It'll tell you every single process running on your PC and will tell you if thinks it recognizes any as dodgy.

Or you could try AVGs Anti-Malware. They do a free version.

[wduk2005]

thanks for that i'll give it a go