Computer speed

[#1]

Hi can anyone help?
I have a laptop with norton installed & have regular signs coming on screen saying "High CPU usage".
What does this mean & does this explain why my computer is slow or even sometimes useless, & how can I remedy the problem.
I do not understand computer jargon so any replies please be basic.
I would greatly appreciate any ideas
Thanks

[#2]

http://community.norton.com/t5/Norton-Internet-Security-Norton/High-CPU-Usage-message/td-p/403918
and for more options
http://www.google.co.uk/#hl=en&sa=X&ei=d6siT6zvBuLU0QWR6PjNCg&sqi=2&ved=0CCUQBSgA&q=norton+pop+up+hi...
However taking the problem of the laptop being very slow can you advise the model of laptop, how much memory it has and which version of Windows and Norton you are using