>>Going back to square one on this :
>>Doesn't IIS on XP impose a 10 connection limit ?
>>Just a thought. I'm not even sure that's correct or whether it may be relevant.......
>>Even if it doesn't affect your app it will likely cause Fiddler to wobble.
>
>But since I hosted my service in a console app, IIS wasn't even involved ... so no, that's not it. <g>

Maybe the XP limitation applies to HTTP connections in general - i.e. not IIS specific. Sorry, I haven't had time to follow this line for myself and could easily be completely wrong,.......