[support] Strange behavior of upload in drupal.js

[luca capra]

Hi all,

I've got a multisite installation of drupal 5.10. In the main domain, 
when adding an item via upload form (or imagefield) the server  give me 
back an error keeping the animation running.

The #redirect-target has inside the json data but trought firebug I get 
a "data is null" referred to line 131 of drupal.js
This is caused I think by this line (about 56)

/response = (iframe.contentWindow || iframe.contentDocument || 
iframe).document.body.innerHTML;

/that say (from console.log)
"Permission denied to obtain the property Window.document"

This happens on various browsers and only in the main site (upload in 
subdomains works well). (maybe a theme related error?)

Did somebody ever had a similar problem ?

Cheers,
 Lu