Maintenance Plan Fails

I created a maintenance plan to back up a database. It fails and I get the follow error in the log file.

Microsoft (R) SQLMaint Utility (Unicode), Version [Microsoft SQL-DMO (ODBC SQLState: 42000)] Error 4064: [Microsoft][ODBC SQL Server Driver][SQL Server]Cannot open user default database. Login failed.

What user is it referring to? What user does a Maintenance plan use to login as? SA on the server has full access to all databases. SAs default database is master and I can read and write to it with the enterprise manager and query analyzer.

All replies appreciatedWhat's your security model?

Are you logged on and manually running it, or is it failing during a scheduled run?

That doesn't sound like a maint plan error though...|||It fails during a scheduled run.

In the Enterprise Manager if I right click on the database > All Tasks > Backup Database it works fine.

In the Enterprise Manager if I go into Management > New Maintenance Plans, schedule it. It fails.

The SQL Server use allows Windows Authentication or SQL Server Authentication. The server in question was registered in the Enterprise Manager with SQL Server Authentication. I don't know if that has any bearing on how Maintanence Plans are queued or what login is used when a plan executes.

Maybe I'm looking at a ODBC Driver problem. I just don't know how to get the details on which driver is being so I can compare it to my other servers where all Plans work fine.

Thanks for the reply.