If when migrating from 2003 to 2008 R2 AD and one 1006 event appears in the eventivewr (DCs was causing the new Windows 2008 does not properly get your computer GPOs) is solved by installing the following hotfix on Windows 2003 DCs:
http://support.microsoft.com//kb/939820
Apparently this problem may be that in the past an authoritative restore of the domain was make and, according to the KB, this causes a KDC problem.