I would also check to see how much memory is being used by this application. If you are short on memory, the swap out to disk will consume lots of CPU time. If the drive space is tight or badly fragmented you will also drive the CPU use way up.
Once you sort the services by CPU you can also check how much RAM is being used, and if you are exceeding the installed RAM, you are swapping to disk. Rebooting may recover lost memory leaks, especially if the system has been up for a long time. Check the memory use in task manager before and after the reboot to see what happens. If you recover a lot,then youneed to find where the leak is coming from and fix it, if possible, or at least throw more RAM at the system to allow it to function in spite of the leak.
At this point there is something else to try. Create a swapfile on another drive (temporarily), then remove the swapfile on the system drive. Then defrag the system drive and re-create the swapspace on the system drive and make it fixed size (2x RAm or more). This will make sure the swapspace stays unfragmented, and greatly improve performance.
The other area of concern is available space on the drive with the swapfiles. Windows likes to have at least 10% of the total drive space free, or it begins to complain, so if the drive space is tight, look to free up and remove garbage (especially temp files and cookies!). Remember 10% of a 10GB drive is a large amount of space (1 GB), and if you start to eat into it the fragmentation begins to rapidly climb and performance falls.
I have also seen Explorer as a major culprit in the high CPU use, and more than once it has grabbed 100% of the CPU and hangs on for dear life, even when there are no open applications. Compare this system to other similar system to see if there are an excessive number of applications running in the Task Manager also. My web server has 41 of 71 listed services actually running, for example.
A final suggestion, install and run the free program called AdAware from
to see if you are losing a lot of CPU time to spybot programs. You will be very surprised at what all it finds running on your system that you never installed and do not know about.
HTH
David