problem with sys audit

my db server is sql server 2000 . when I set up a sys audit and click the enable system audit button. The db audit will auto restart my sql server. when the sql server was start. the db audit display a error messagebox. and have some error report in system event management.
the error is :
[Microsoft][ODBC SQL Server Driver][SQL Server]user '(null)\(null)' log fail. (I use chinese opetation system. so i translate it .)

Audit event reader process is unable to connect the database!.

Hi,

You don't have to restart the SQL Server right away. You can click the No (translated) button on that dialog and choose to restart SQL Server later when it is convenient for you. It is just the installed auditing will not start working until the server is restarted.

The reason for this error is that DB Audit back-end auditing process is having problems connecting to the database server. Most likely you specified a connection using SQL Server authentication, which does not work quite well. For the installation you should login using Windows authentication. After the installation you can login any way you want.

You can find additional diagnostic messages in the Windows Application Log on the server.