Sql-server – Security for Oracle linked server from SQL Server

As one colleague pointed out, there's no SQL Server 2003 version. I suppose you're speaking about MSSQL 2000. Which was somehow related in time with VS 2003 :-).

As you're working with instances on the same server, do you have the service "SQL Server Browser" started and running?

Why you need it:

"The SQL Server Browser program runs as a Windows service. SQL Server Browser listens for incoming requests for Microsoft SQL Server resources and provides information about SQL Server instances installed on the computer. SQL Server Browser contributes to the following actions:

Browsing a list of available servers
Connecting to the correct server instance
Connecting to dedicated administrator connection (DAC) endpoints

"

This is expected. LUA strips administrators membership from your token. From Getting Started with User Account Control on Windows Vista:

To help prevent malware silent installation and computer-wide infection, Microsoft developed the UAC feature for Windows Vista. Unlike previous versions of Windows, when an administrator logs on to a Windows Vista computer, the user’s full administrator access token is split into two access tokens: a full administrator access token and a standard user access token. During the logon process, authorization and access control components that identify an administrator are removed or disabled, resulting in a standard user access token. The standard user access token is then used to launch the desktop, the Explorer.exe process. Because all applications inherit their access control data from the initial launch of the desktop, they all run as a standard user as well. Contrasting with this process, when a standard user logs on, only a standard user access token is created. This standard user access token is then used to launch the desktop.

Since your local desktop token has the administrator membership removed, it cannot log in locally to SQL Server if you expect to log in through builtin\Administrators. On remote access your token preserves the Administrator membership and you gain access.

The solution is to grant SQL Server login rights through an explicit domain group account and add all users that require access to your SQL instance to this domain group. Do not rely on Administrators membership, is a bad practice.