I am experiencing trouble establishing a connection to an SQL2000 DB using
trusted copnnections from a Excel2002\VB app for only 1 user on 1 machine.

When I try to establish the connection I recieve the following message

Connection failed: SQLState: '28000' SQL Server Error: 18456
[Microsoft][ODBC SQL Server Driver][SQL Server]Login failed for user
'Domain\ProblemUser'.

Does anyone have any ideas on how to resolve this issue without having to
re-load the OS?

If I log in as other users on this machine the connection works.
This user is part of the Local Administrator Group as well as a Public Group
in which others users have the same rights and can connect.
This user can log in from other terminals and the connection works. Other
users can log in from her terminal and the connection works.

The SQL server is SQL 2000 Fully Patched
The Workstation is XPSP2 fully patched
The Office (EXCEL) version 2002 is fully patched