Hi Chris
This is a known issue and we regret any inconvenience caused to you.
When you export the HTML from the web layout an image folder alongwth the HTML file is created.
This image folder would have 2 SWF files , one of the main Interactive layout and the other of the nested layout.
To work around the problem faced by you , simply move the swf of the nested layout from the image folder to the main folder containing the HTML file and the Image folder.
Hope this helps , please feel free to get back for any other further queries/comments.
Regards,
Kabir