URLLoader returns no data in debug environment

The problem involves a URLLoader that GETS some XML for the user profile from a web server. It started recently when I got a new iMac with OS 10.7.4 and installed Flash CS6 trial to see if I want to upgrade instead of reinstalling CS3.

The URLLoader has always worked fine before but now returns no data in the debug enironment. Security sandbox should not be an issue since it is in the debug environment. If I upload the compiled SWF and test it in the browser it works perfectly (loads the user profile). I made certain that the version for the brower test was the same one I just compiled by incrementing the version number displayed in the SWF graphics.

In the development environment, the URLLoader successfully connects to the server, generates the open and complete events and does not generate any error events. However, the data variable contains just an empty string after the complete event instead of the XML from the server. Tracing with tcpdump shows there really is a TCP connection to the server with data passing over it. I can perform the same GET request directly in my browser and it works fine, so I know there are no DNS or networking issues between my computer and the server.

I cannot do any more work on this project until I can get this issue resolved.