jQuery Call to WebService returns "No Transport" error
Add this: jQuery.support.cors = true;
It enables cross-site scripting in jQuery (introduced after 1.4x, I believe).
We were using a really old version of jQuery (1.3.2) and swapped it out for 1.6.1. Everything was working, except .ajax() calls. Adding the above line fixed the problem.
If your jQuery page isn't being loaded from http://localhost:54473 then this issue is probably because you're trying to make cross-domain request.
Update 1Take a look at this blog post.
Update 2If this is indeed the problem (and I suspect it is), you might want to check out JSONP as a solution. Here are a few links that might help you get started:
I had the same error on a page, and I added these lines:
<!--[if lte IE 9]><script type='text/javascript' src='//cdnjs.cloudflare.com/ajax/libs/jquery-ajaxtransport-xdomainrequest/1.0.3/jquery.xdomainrequest.min.js'></script><![endif]-->and it finally works for me ;) no more error in IE9.