打开下面path的web.config文件:
C:\Program Files\Common Files\Microsoft Shared\Web ServerExtensions\12\TEMPLATE\LAYOUTS

修改：
<system.web>
...
 <customErrors mode="Off" />
...
</system.web>

如果没有就添加：
<SharePoint>

<SafeModeMaxControls="200" CallStack="true" DirectFileDependencies="10"TotalFileDependencies="50"AllowPageLevelTrace="false"/>

</SharePoint>