Error when user authentication in AD

[Grey]

I am using ASP.NET to authenticate use with AD. But, when the web.config of
my server set , '<identity impersonate="true" />', I got an error
"An error occurred while try to load the string resources (GetModuleHandle
failed with error -2147023888). ". When I remark it, the form can load. When
is the function of '<identity impersonate="true" />'?? Do I need to set this
when doing form authentication??? How to solve the error if use the identity
attribute in web.config


Million Thanks