Vista using 100% cpu??

Hi Guys

my mums laptop is running at 100% cpu even though no programs are running. checked the processes and there were a lot of svchost processes running, closed them down but still the same, started a malware scan on the laptop in the hope that might help, as it looks like a virus to me the physical ram is 2gb installed on the machine, anybody out there got anymore ideas on what it could be??

as always thank you
David