100% CPU Usage by SVCHOST

Hi techy people,
I have recently noticed that my computer has become very slow and hangs a lot. Most of the times I need to restart it. After restarting, it works ok for a few minutes and then becomes very slow again and hangs as soon as I start opening different applications.
I checked the task manager and noticed that my CPU usage is 100% and that a SVCHOST process is causing this. What is this process and how can i prevent it from using all of my CPU processing power?
When I stop this process after a while it starts up back by itself.
I have Windows 7 installed on my machine.
Please help.
