I'm running Windows Server 2003 Standard (Much to my distaste), I've applied all the security updates and now I'm stuck with a box that's constantly being hammered by svchost.
The process ID is always around the 700 mark and if I use tasklist /svc, I can see that RpcSs is causing it.
I have tried various things that have come up in google searches such as turning automatic software update services off, removal of antivirus software, removal of systray items, removal of remote screen services such as RDP, VNC, LogMeIn etc.
I'm still stuck with this RpcSs running at 90%, I'm completely at the end of my tether with this now but I don't really want to sit through a complete re-install just to see if it happens again.