I get this error using IE 8 and just upgraded to WordPress 2.8.4
Webpage error details(this is a error that IE reports)
User Agent: Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 5.1; Trident/4.0; GTB6; .NET CLR 1.1.4322; .NET CLR 2.0.50727; .NET CLR 3.0.4506.2152; .NET CLR 3.5.30729)
Timestamp: Mon, 17 Aug 2009 01:05:19 UTC
Message: Type mismatch.
Line: 1
Char: 4855
Code: 0
URI: http://static.addtoany.com/menu/page.js
Message: Type mismatch.
Line: 1
Char: 4855
Code: 0
URI: http://static.addtoany.com/menu/page.js