Svchost covers a pile of different services under different Process ID's
I.E. svchost PID 408

I.E. svchost PID 752

I'd guess you used Task Manager to shut down the svchost entries and accidentally killed Remote Procedure Call...which forces the system to shut down.

You can get around this by using Procexp and either killing the svchost entry the rogue service is running under, or suspending it (hopefully stalling the shutdown procedure).
http://technet.microsoft.com/en-us/sysinternals/bb896653.aspxBtw, this comes in well handy for those Viruses that just pop up under a different name while you're trying to remove them. If you suspend them, you can get to work removing the bastards while they think they're still working.
