follow this kb article and note the special instructions for windows server 2003. it specifies "to configure windows server 2003-based domain controllers, use the net logon service group policy "priority set in the domain controller locator dns srv records".
- launch the local policy editor by using gpedit.msc
- drop down administrative templates
- navigate to system/net logon/dc locator dns records
- enable the setting "priority set in the dc locator dns srv records"
- adjust priority to proper value