After installing Oracle 10 Release 2, you want to use the Enterprise Manager (EM) to schedule a backup of the databases. However, in the end it asks for logon credentials for the operating system (So, for a user account of the OS, not of Oracle). Even tho you entered "Administrator" or any other username + the correct password, it barks about user/password not being accepted. Strange.
[Solution]
In the local security policies, you have to enable a user to "logon as batch job". Best is to create a Oracle_Backup User who can't do anything but the most necessary things, + logging on as a batch job.
Use that user, and be surprised; It works that way
