Are you seeing this when testing AND still being logged into the CMSDesk or CMSSitemanager? If so, log out of the CMSDesk or Site Manager and see if your problem persists. You can also put this in your master page layout if you want to include the jQuery UI and NOT the jQuery UI CSS.
<script runat="server">
protected void Page_Load(object sender, EventArgs e)
{
CMS.GlobalHelper.ScriptHelper.RegisterJQueryUI(this.Page, false);
}
</script>
I add the jQuery UI CSS in the master page manually as I want it to be loaded prior to any default App_Theme stylesheet.