I have the same problem with a TW built VT tour. TThe original company that created, using thius software, no longer exists so I'm getting no real support.
I've tried all possible combinations of twviewer.swf files, as per this forum, but the problem still exists and displays the same symptoms.
The tour begins to load and then hangs at the 20% mark. I've also tried clearing the browser cache, various different browsers etc. all to noavail.
Is there any new update on this issue.