CPU Usage 50% all the time

I have been having trouble recently with the computer seeming very slow. I have noticed that when checking with System Monitor the CPU usage is showing 50% with all programs except system monitor closed. Also the Dial-up Adapter Connnection (sic) Speed shows 9600k at all times even when I'm not connected- jumping up to 40000ish when I actually connect.

Is this normal and if not has anyone any suggestions?

I've tried Ctrl-alt-del and closing everything down but it makes no difference.