Yes, i've got a similar problem but get a ViewExpiredException when remoting from an iframe in IE, (works fine in firefox). I tried many different things but was unable to resolve.
The Seam team (or at least Angel of the Lord) does not like IE. Try using IE with this site. You'll have some problems.
Most likely your issue is a bug in IE and/or Seam.
Sad but true, I feel less alone with you all having my same problem. The tag in my page is
and as you already told it perfectly works in Firefox (the image is visible) but not in Explorer 6 or 7 (the image is just an empty thumb).
Anyway if anyone find a workaround-solution do not forget to share it :)
To specify better my previous sentence. The s:graphicImage is into an iframe anway when outside of it it works perfectly also in Explorer.