We've just upgraded to vs 6.0 from 5.5r2

We have a form that we use to create News for our site. One of the form element uses the "Uploader" Form control type to upload an image when needed.

The problem is when we don't need an image (and leave the field empty) the Uploader form control is automatically entering "00000000-0000-0000-0000-000000000000" into the database field on submit. It was putting " NULL" into the field before the upgrade. This is causing problems by creating broken image link on our News pages. This worked before the upgrade to 6.0.

The problem is happening before the display logic, but here it is:
<div class="image">
<%# IfEmpty(Eval("StoryImage"), "", "<img src=\"" + GetFileUrl("StoryImage") + "\" alt=\"Story Image\"/>" ) %>
</div>

Here's a link to one of our news pages with the broken link. Use IE to quickly see broken link:
http://www.fdle.state.fl.us/Content/News/FDLE-arrests-Jacksonville-man-for-capital-sexual-b.aspx