Price Shows As NaN With Dynamic Price Update Enabled

I have dynamic price update enabled and it works fine for products with multiple attributes, but for products with 1 attribute and the price is 0 for the attribute it changes the price to NaN

Anyone else experienced this and knows a fix?  Save me an hour or so if you could share?

Bit of a hack, but on the last bit of the JavaScript in the productattributes.ascx module I changed the following to fix it.

        if(res != 'NaN')
        {
            $(".<%=PriceVarClass%>").text(res);
        }

Thanks for info. Here is a changeset with a fix http://nopcommerce.codeplex.com/SourceControl/changeset/changes/57283