ASP.NET 拒绝访问

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使用microsoft的com组件编写插入数据到excel然后再下载到客户机本机程序，在开发时测试通过，上传到win2000服务器上后出现如下错误:
  server error in '/webqr' application.
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拒绝访问。
description: an unhandled exception occurred during the execution of the current web request. please review the stack trace for more information about the error and where it originated in the code.

exception details: system.unauthorizedaccessexception: 拒绝访问。

asp.net is not authorized to access the requested resource. consider granting access rights to the resource to the asp.net request identity. asp.net has a base process identity (typically {machine}/aspnet on iis 5 or network service on iis 6) that is used if the application is not impersonating. if the application is impersonating via <identity impersonate="true"/>, the identity will be the anonymous user (typically iusr_machinename) or the authenticated request user.

to grant asp.net write access to a file, right-click the file in explorer, choose "properties" and select the security tab. click "add" to add the appropriate user or group. highlight the asp.net account, and check the boxes for the desired access.

由于本机测试的时候就出现这种情况，在网上查找解决方法，尝试解决的方法如下：
1。提高iis_user的权限，将iis_user加入administrator，个人觉得这样做有安全风险，故不采用
2。在开始－》运行 输入dcomcnfg配置，excelcom文件的安全性权限，编辑启动权限，配置权限
修改完成后出现错误
  server error in '/webqr' application.
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object reference not set to an instance of an object