Thanks for your post!
Hm that's interesting, I don't think I've seen this error come up before starting an IIS profilng session.
When it's thrown, could you kindly send in an error report to Red Gate with your email address so I can check the unobfuscated stack trace?
Can I also check--are you profiling on the original port or an unused port? Is the error thrown either way?
Red Gate Software Ltd.