Login Failed for user "NT Authority/Anonymous user"

HI,
i am developing a web application which sholud be accessible for only domain users(NT Athuntication) with database SQL SERVER 2000 with NT Athuntication.It is working fine if i am accessing from local system with address"HTTP:\\Localhost\applicationname".But where as if i am accessing with "HTTP:\\IPADDRESS\applicationname" after 10 mints it showing the error "Login Failed for user "NT Authority/Anonymous user". Can any body tell me the solution for this.
im using the fallowing connection for above said application problem.
Connection string "Intigrated security=sspi;databasename=XXX;server=ZZZ";

in the web.config i made impesrsastion=true;windows authuntication.

in the IIS i disabled Anonymous user access.Only intigrated windows security enabled.

Thanks in advance
satishHi,
if you are using IE have you set Enabled Integrated Windows Authentication off the Tools/Internet Options/Advanced tab?
I think it is not requried. :rolleyes:
How are you passing the credentials?
No need of passing the credentials.