As Tony mentioned if you still have trouble, you could go to the Configuration Items table, create your filter exactly how you want it, then right click the filter and "Copy Query".  Go back to your Configuration Item dictionary page and change the Reference Qualifier from Simple to Advanced and paste your query in there.  It would look like this:

sys_class_name!=cmdb_ci_dns_name^sys_class_name!=cmdb_ci_vmware_instance^sys_class_name!=cmdb_ci_db_mssql_database^EQ