IE 7, Beta 3 isn't a full release version. The fact that anything works or doesn't work in it is basically meaningless, although one would assume that it is more standards compliant than IE 6. Still, even this cannot be certain for any particular layout, design or script feature.
Please include a link to the DD script in question in your post. See this thread
for the proper posting format when asking a question.
Please post a link to the page on your site that contains the problematic script so we can check it out.
I see you have typed that you cannot comply with this second request due to privacy reasons. In that case a link to a live page or the full code of a page which demonstrates the problem you are talking about would be required.
However, unless your page isn't intended to ever be on the internet, I see little reason why it could be private, though there could be exceptions. Remember, the internet is a public medium.