Ack. Now I'm confusing myself even more. Maybe working backward
from the desired result will help:

Row 3 is selected because for column A value 12345, 05/11/05 in column
D is after 01/01/05 in column B (on the same row) and before 05/01/06
in column B (on the next row).
1 :12345 01/01/02 3 05/11/05
2 :12345 01/01/03 3 05/11/05
3 :12345 01/01/05 N 05/11/05 TRUE
4 :12345 05/01/06 T 05/11/05


Row 6 is selected because for column A value 56789, 10/12/06 in column
D is after 02/01/06 in column B (on the same row) and there are no
later column B dates for 56789 (the next row has a different column A
value).
5 :56789 04/01/04 2 10/12/06
6 :56789 02/01/06 N 10/12/06 TRUE

Row 7 is selected because for column A value 68765, 07/31/05 in column
D is after 01/01/99 in column B (on the same row) and before 10/01/06
in column B (on the next row).
7 :68765 01/01/99 3 07/31/05 TRUE
8 :68765 10/01/06 2 07/31/05

Row 9 is selected because for column A value 80101, there is only a
single row and, by default, this has to be the correct record.
9 :80101 01/01/05 N 08/24/06 TRUE

Row 10 is selected because for column A value 95555, 04/13/05 is after
01/01/99 in column B (on the same row) and before 05/01/06 in column B
(on the next row).
10:95555 01/01/99 N 04/13/05 TRUE
11:95555 05/01/06 3 04/13/05
12:95555 10/01/06 T 04/13/05

Sorry so wordy.