我新建了一个Discussion Board，然后修改了NewForm.aspx，将自带的ListForm WebPart删除，添加了Custom List Form，之后Allitems.aspx页面在Sharepoint Designer里显示正常，在浏览器浏览的时候报错，报错信息如下：
Unable to display this Web Part. To troubleshoot the problem, open this Web page in a Windows SharePoint Services-compatible HTML editor such as Microsoft Office SharePoint Designer. If the problem persists, contact your Web server administrator.
后来找了好久的原因，才发现不能将自带的ListForm WebPart删除，只能将其设置隐藏。