Symptom:
System always asks to input the username or password even you input the correct ones.
最近用Windows 7访问共享目录，老是失败，一直提示输入用户名和密码界面。开始以为是用户有问题，后面创建了新的用户，还是访问不了。
查了一下，需要修改一个组策略的配置项。（参考下面）
Environment:
Windows 7.
Solution:
1) Open Local Group Policy Editor: Windows Menu -> Run -> "gpedit.msc"
2) Find the item: Computer Configuration -> Windows Settings -> Security Settings -> Local Policies -> Security Options -> Network security: LAN manager authentication level.
3) Update the value: By default, it is not set -> Update it to "Send LM & NTLM" responses.