My first suggestion is to tidy up the data on your HDD so please follow the directions provided below starting with Autoruns http://technet.micro...ernals/bb963902
1: Extract the Autoruns Zip file contents to a folder.
2: Double-click the "Autoruns.exe".
3: Click on the "Everything" tab
4: Go to File then to Export As or Save in some versions.
5: Save AutoRuns.txt file to known location like your Desktop.
6: Attach to your next reply.
2nd: Download and run TFC from http://www.geekstogo...ds&showfile=187 your computer should automatically re-boot on completion but if not do it manually.
3rd: Defrag your HDD http://www.auslogics...re/disk-defrag/ a tidy drive is a faster drive, please note that I am not suggesting that you use any other product or service at the link.
Couple of other things to consider are what size HDD do you have and how much free storage space is available, you should always have between 12 and 15% of the overall capacity available, do not have more than 1 AV program running as it causes slowness as the programs fight for control of system resources, this can lead to instability and/or crashes.
What AV do you use, some use a lot more system resources than others Norton and AVG are excellent but very demanding.
To speed up your boot times find any unnecessary programs linked to start up "how to" below;
START -> RUN
type MSCONFIG in the RUN box
then click OK
Click on the start-up TAB
Look at each line that has a check in the box, these are start-up items, with the exception of Windows programs and your anti virus software uncheck the ones you do not want to run at start-up.
If the CPU usage remains high after following the above steps you may need the assistance of the experts over on the malware forums as malware is another possible cause of such behavior.