I am not sure how much big your directory is?
Have you tried some thing like this?
<img id="busy" src="busyIcon">
<cfdirectory action="list" directory="E:\" name="myvar" >
<cfdump var="#myvar#" >
code for hide busy icon.
I know this is looking odd but you can try this.
just a quick post!
Have you checked the view soure, just want to know coldfusion is sending blank response?