What is this svchost.exe (LocalServiceAndNoImpersonation) using all my CPU?

If you've got Win7 you can find out which actual service is using your CPU via the Resource Monitor, ResMon.exe.

On the CPU tab, the second frame down is "Services" You can right-click on the offender and stop it. Often a stop and restart will fix it, at least till next time.

svchost.exe (LocalServiceAndNoImpersonation) using about 30% of core i5..