求助下关于模拟登陆并获取数据，总是返回500错误

f4991417

http://qfoa.qfkd.com.cn/setqfkd/login.aspx

这个是需要登陆的地址

我现在是用户输入用户名密码和验证码，然后软件自动获取登陆后的一些东西


我之前做过几次尝试，都是当天可以，然后第二天又出现500错误，不知道为何

附上抓包数据，请教各位，谢谢


POST http://qfoa.qfkd.com.cn/setqfkd/login.aspx HTTP/1.1
Host: qfoa.qfkd.com.cn
Connection: keep-alive
Content-Length: 369
Cache-Control: max-age=0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8
Origin: http://qfoa.qfkd.com.cn
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/31.0.1650.63 Safari/537.36
Content-Type: application/x-www-form-urlencoded
Referer: http://qfoa.qfkd.com.cn/setqfkd/login.aspx
Accept-Encoding: gzip,deflate,sdch
Accept-Language: zh-CN,zh;q=0.8
Cookie: pgv_pvi=9947412480; DTRememberName=021322; ASP.NET_SessionId=lfv2a4ijxtvktbd5g2hkw45h

__VIEWSTATE=%2FwEPDwULLTE0MzMzODc5NjBkGAEFHl9fQ29udHJvbHNSZXF1aXJlUG9zdEJhY2tLZXlfXxYBBQxjYlJlbWVtYmVySWTPcQjmbVHbY5ROIjhheAG6wX4ZddmDUCTSNRv3bsr29w%3D%3D&__EVENTVALIDATION=%2FwEWBgLwqPfRDAKl1bKzCQLG8eCkDwLChPzDDQLDndTvCQLCi9reA6IQRWHHty8LBx4WPNgyvaMkfd0Lw0ssUwITGB095wdc&txtUserName=021322&txtUserPwd=qf123456&txtCode=MALH&cbRememberId=on&btnSubmit=%E7%99%BB+%E5%BD%95








GET http://qfoa.qfkd.com.cn/setqfkd/index.aspx HTTP/1.1
Host: qfoa.qfkd.com.cn
Connection: keep-alive
Cache-Control: max-age=0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/31.0.1650.63 Safari/537.36
Referer: http://qfoa.qfkd.com.cn/setqfkd/login.aspx
Accept-Encoding: gzip,deflate,sdch
Accept-Language: zh-CN,zh;q=0.8
Cookie: pgv_pvi=9947412480; ASP.NET_SessionId=lfv2a4ijxtvktbd5g2hkw45h; DTRememberName=021322; AdminName=QFoa=021322; AdminPwd=QFoa=7FDBDC5BD51B60A049120017B66A5A2A