Unable to Login Universe Design Tool in client system

Hi,

We are using SAP Business Objects 4.0. When I am trying to login to Universe Design tool it is showing the following error.

"[repo_proxy 13] SessionFacade::openSessionLogon with user info has failed(Unable to log on: Could not connect to server. Please check that the server name is correct, and that the server is running.

(hr=#0x80042a01)"

Last week it was working fine, but suddenly I am facing this problem in my system. In other client systems it is working fine.

Could you please suggest me how to resolve this issue.

With Regards,

Sriram