It appears to be your "slick RSS" module. After unpublishing this module the error no longer occurs in IE7. I would check with the developer of this module and see what they suggest.
Regards,
My client reports the same issue - I don't use I.E. What do you mean by his "slick" RSS feed - the button that installed with the site shaper in the top black bar?
If I delete that reference from the index.php - can I expect this message to go away?
The client is highly troubled by this. Thanks.