If you’re pc is showing symptoms like these:
-Your system becomes sluggish and you find that something called svchost or dllhost is taking nearly 100% of your CPU.
-Your system reports that svchost has performed an illegal operation and will be terminated. After that various things fail to work properly, if at all.
-After you log in, your system automatically reboots in one minute.
It's almost certain that you either have a virus or your system is currently vulnerable to a particular type of exploit known as the "RPC buffer overflow".
Take a look on this link. This should help you on your problem. It has definitions and remedies to consider. I downloaded some for myself for future references. I strongly recommend you visit this link.
Svchost and Svchost.exe - Crashs, CPU maximization, viruses, exploits and more. - Ask Leo!