Application giving 401 error on 1 server, but working on other


I have an Twitter Application, which has been working perfectly for some time now.
But since 1-9-2012, it has stopped working, it gives 401 error.
But when i re-installed it on another server, it has started working again.

Here are the details:-

Consumer key oYhg3YRGCU5vzvvlm1yCEQ
Consumer secret ZneULhTdCclpb5flrAh8187kPjB31oraXmnm2k1iY0
Access token 446134324-7xA8quNUd3eqCoVZKSyr7ZA9iu0or5yO6ClTo7MV
Access token secret 2b2ORIcrkoq533QsJ2mD7LgQVEnlf1XrI1lbkFlOeF0
Access level Read, write, and direct messages

IP of server, on which it stopped working :