In SQL Server 2005 the old style outer joins used are no longer supported from bol:
Old-Style Outer Joins Earlier versions of SQL Server support the definition of outer joins that use the *= and =* operators in the WHERE clause. SQL Server version 7.0 supports the SQL-92 standard. This provides join operators in the FROM clause. When the compatibility level of the database is set to 90, the outer join operators (*= and =*) are not supported.
This means that you have to run the Opmanager database under compatibility mode for sql server 2000.