Just a really simple project WCF client -> wcf service hosted in IIS. A couple of strings passed in and an bit of DB access via EFv1 to sql 2008. Everything works fine then you make a request and IIS doesn't respond and the client times out and no more requests processed. This is low volume, 20ish transactions a minute while testing.
Nothing in the logs, no high CPU, nothing. Only way to get it working again is iisreset.
This is on two of my machines that are Win7 RC. Both these also have VS2010 beta1 on them, so I'll give it a go on a machine without 2010 and see what happens.