401 - Unauthorized error while connecting to userprofile web service in InfoPath 2010

Hello,

I have 2wfe (NLB), 2app, 1db farm.

Everything is working fine except for one computer! I have several InfoPath forms, they have custom webservices and userprofile web service. They work without any problem, but there is one computer that gives me 401-Unathourized Error! I'm not sure it is double hop issue because there is no other user/computer we are having a problem!

I checked several blogs, they refer to hosts file, but not sure because why is it happening only on one computer?

I have hosts files refers to 127.0.0.1 webapp .

What could be the issue? I have other Service Apps are working without any issues.

Could you please help me?

Thank You

Orrin