I've noticed an unusual process starting up after I installed Visual Studio .NET 2005 b2.
mscorsvw.exe is .net 2.0's assembly optimizer. The good news is; it starts up and works away in the background optimizing .net assemblies for your pc. However I did notice, when installed on WindowsXP SP1 that has been upgraded to SP2 the mscorsvw.exe process starts up and claims an unbearable amount of CPU.
It is apparently supposed to optimize in the background after it does your core assemblies which should apparently only take a few minutes. If it doesn't you've got a problem.
My solution come coincidently when my install of windows conveniently died a week or two after, so I installed a combined fresh copy of WindowXPSP2 and the problem never appeared. So my only conclusion is it might have been something weird happening with .net 2.0 and my install of XPSP1 upgraded to SP2
For more information see this article which may answer any other questions: What is mscorsvw.exe and why is it eating up my CPU? http://blogs.msdn.com/davidnotario/archive/2005/04/27/412838.aspx