[Plugin: AddThis] doesn't share image or description

I’m trying to install AddThis, but it really doesn’t work:

(1) When I test sharing on facebook, there’s no title, no description or image.
It does share the correct url, plus the previous title and tagline of my site (possibly cached in google). This happens with both Firefox and IE (I haven’t tested other browsers).

(2) In IE 8 there’s an “error on page”. Details:
User Agent: Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 5.1; Trident/4.0; .NET CLR 2.0.50727; .NET CLR 3.0.4506.2152; .NET CLR 3.5.30729; eMusic DLM/4)
Timestamp: Tue, 22 May 2012 21:06:27 UTC
Message: Unknown runtime error
Line: 2
Char: 3630
Code: 0
URI: http://s7.addthis.com/js/250/addthis_widget.js#pubid=ra- ..etc…

(3) When I try a facebook share, Facebook’s “Share This Link” opens in a new Firefox tab …not a pop-up. Worse, in IE 8, the “Bookmark & Share” popup doesn’t display when I hover… when I click it takes me to a new page, http://www.addthis.com/bookmark.php?v=250

My configuration:
* wordpress 3.3.2
* theme: coraline 1.2
* AddThis plugin/widget: 2.3.2
* my site is hosted using a domain alias & htaccess rewrite, not sure if that could be related. I’ve also done some WordPress hardening, as recommended at http://codex.ww.wp.xz.cn/Hardening_WordPress

Thanks for any suggestions!

http://ww.wp.xz.cn/extend/plugins/addthis/