I am currently having a problem with a windows 2008 server running IIS 7. The server runs several sites but only seems to have the issue with one particular site.

Every so often, the whole server slows to a crawl with nearly all requests timing out! Invariably, when we log in to take a look there is always an IIS process using up around 90% cpu. Looking into the worker processes in IIS there are usually one or two requests that have been running for a long time. They are always in the ExecuteRequestHandler state with ManagedPipeline as the module name and the current ones i'm looking at have been running for 7686248 (what units is this in, it doesn't say?). It is also not always the same page, in fact we have seen at least 3 different pages listed under url when this has happened.

It seems that the only way to bring the server back to life is to kill the 90% process!

The site is running under .Net 4.0 and the code on it is very similar to other sites on the server which do not have the problem!

How do I start troubleshooting this?