Same problem. You ever figure out why?

I have a very similar problem. It seems to be that when PIE.htc is used it gets loaded twice. The first load gets aborted, but not like a normal abort with an error code, the data is simply truncated. A subsequent load a few ms later works OK. It seems that if the correct fully loaded copy is present in cache, then it is fine.
The problem is quite strange and seems like a bug in IE.

I'm seeing the same truncated download of PIE.htc in IE9 as ladz mentioned above.
I've attached a screenshot of the network traffic from IE's developer tools showing PIE.htc being downloaded twice. The first time it gets downloaded it is truncated, only 8kb instead of 40kb.
Any thoughts about what may be causing this?

Unfortunately the loading of the htc file is handled completely by IE, and I have no visibility into how it does that. If someone is able to find a pattern to what causes it to sometimes download twice and sometimes only once, that would be helpful to help users avoid it. But from a code standpoint there's nothing we can do within PIE itself to prevent the double download.

However, in the 2.0 codebase on GitHub, PIE has been rearchitected to try to lessen the cost of this double download. The .htc file has become a very small (~1kb) loader file which makes a subsequent request for a secondary logic file, specific to the browser version. This means that even if the .htc is downloaded twice, that cost is very small. Hopefully this will help alleviate the situation.

Looks like I figured out the root cause of the truncated download of PIE.htc. The apache server was missing some gzip configuration.
Added the following to the httpd.conf file:
AddOutputFilterByType DEFLATE text/x-component

I also had to use the 2.0 version of PIE has well. Thanks for the suggestion.