一直运行得很好，我下了SharePoint Designer2007来修改一些页面文件后，整个网站挂掉了，报错：
Description: An error occurred during the parsing of a resource required to service this request. Please review the following specific parse error details and modify your source file appropriately.
Parser Error Message: Data at the root level is invalid. Line 1, position 1.
Source Error:
Line 1: <browsers>
Line 2: <browser >
Line 3: <controlAdapters>Source File: /App_Browsers/compat.browser Line: 1
原以为是/App_Browsers/compat.browser被sharepoint designer 2007修改了文件编码方式，查验后发现文件编码没变。
后来google后才知道，为了支持FrontPage扩展，sharepoint designer 2007自动在虚拟目录下每个文件夹里加了一个_vti_cnf文件夹，将所有_vti_cnf文件夹删掉，everything back!!
related links:
Edit file in Wss3 web application with SharePoint Designer blows up your web site