WYSIWYG doesn't load

Hello.
I have an issue: anytime when using WYSIWYG it doesn't work and outputs the "Permission denied to get property Window.addEventListener" error.
But it used to work some time before...
Something happened.
It doesn't work in Firefox 3 and IE 8.

You can verify it here:

• go to www.vostrets.ru/xwiki/
• log in as "wysiwyg" (the password is also "wysiwyg")
• click any icon
• try to create a new page there - the wysiwyg won't load

If you want, i can give you any access to my machine (glassfish admin console, ssh or anything else).
Because this is just an issue that makes the whole wiki totally useless..