Account Lockout Problem With Sp_send_dbmail

I am running this code in a job:

EXEC msdb.[dbo].sp_send_dbmail
@profile_name = 'Blah Blah',
@recipients = 'blah@blah.com',
@subject = 'Server Report 1',
@body = '',
@execute_query_database = 'DBInfo',
@query = 'EXEC dbo.usp_SvrRpt1;',
@query_result_header = 0,
@query_result_width = 300,
--@attach_query_result_as_file = 1,
@query_result_separator = '';
GO

Because I am creating a total of 6 server reports, I alter the subject and query like so:

@subject = 'Server Report X' --where X is replaced with values 1 to 6
@query = 'EXEC dbo.usp_SvrRptX' --where X is replaced with values 1 to 6

I can run 4 reports without any problems. If I run more than 4 reports in the same batch, my network account under Windows 2000 Activity Directory is locked out as if I had erroneously mistyped my password the number of time to meet the lockout requirement - in this case, the number is 3 login tries.

Is this a known problem with Database Mail? If so, is there a fix or workaround?

Thanks,

Neal