I have a Access 2007 application linked to a SQL Server 2008 database. This application pops up the following error for some users on the network:
"Connection failed:
SQLState: 28000
SQL Server Error: 18456
[Microsoft][ODBC SQL Server Driver][SQL Server]Login failed for user 'domain\username' "

The db and the dsn is set up to use SQL Server Authentication (the account used is called dbuser (say)). However, when I open the application it seems like it is using the Windows login to authenticate.

Here's what I've done so far to tackle the issue:
* Made sure the computer has the most recent updates
* Connection tests out successfully using the ODBC System/User DSN (The file dsn is configured correctly too)
* SQL Server is set to mixed mode authentication (Windows + SQL Server)
* I can talk to the SQL server through the Management Studio Express using the dbuser account (read/write)

System config:
* MDAC 2.8 SP1
* Windows XP SP3

The MS access application works for another account on the same system. There is this one account that it won't work for, and I can't seem to find out what the problem is.