Extremely High CPU Usage

Hello,

I am having a problem with my computer. It has of late been running at 90+ % CPU usage, and sometimes 100. When i hit Ctrl ALT DEL and open the task manager, the services.exe under the processes tab is using almost all of the CPU. Why is this? I have Norton installed and can find no viruses. The laptops cooling fan is so loud now, presumably cause of the high CPU usage. I am running windows 7, 64 bit.

Thanks so much in advance,

Tom