High Fan Noise and 100% CPU usage by Dock

My MacBook Pro 3.06 GHz Intel Core 2 Duo running 10.6.8 just started making a constant fan noise. When I checked the Activity Monitor, it shows my Doc CPU usage as 100%, and my Percent User Usage is about 52% System 2.5% and % Idle is 47%. These numbers are when there is nothing running except Activity Monitor. When I log out and log in as another user, the high fan noise stops, and the CPU usage of the Doc is <1%. I have tried restarting my computer, Rebuilt my Permissions, Emptied the Trash, and Reset the SMC (I think I did it correctly for the MBPro, but the Power Light did not change, and nothing seemed to be any different on my computer.) I think I recently did a recent Apple Update, but I don't know how long ago that was. But it was sometime in the past few days. Does anyone have any idea about what could be going on?

Thanks,

Frank