I was recently uploading media using the VMware vCloud Director (126.96.36.1994915) console with Internet Explorer (9.0.8112.16421).
On uploading the media, the download and upload transfer progress window would stop responding. Upon closing the window and opening another session, the media was not present in the queue. No error message would be reported until the session inactivity value was exceeded.
The cause of the issue seemed to be we with the version of Java running on the client, in this case the version was 1.6.0_29-b11. Simply by upgrading to 1.70_04-b22, this resolved the issue with the transfer progress window not responding.
The VMware knowledge base only states for the upload functionality that Java version 1.6 and above is required.
In order to upload vApp templates and media to a catalog, the computer from which you are uploading must have Java Plug-in 1.6.0_10 or later installed. In some cases, even after you install the plug-in you will not be able to upload files until you restart your Web browser.
However, this did not seem to be the case in this environment, upgrading to 1.7 resolved the issue, and a brief search on the web did not result in any information on the above being found, so will be interesting to know if anyone else has experienced this problem.