There can be a problem if you connect using ODBC. If you do that,
a. you can't filter in the Edit Recpients dialog box, although you can sort
b. in that dialog, if you select one of the drop-down arrows in a column
header, then Advanced... you may see a message along the lines of "Word
detected Microsoft Query on your system. Would you like to edit <your data
source name> using Microsoft Query?" If you say No, Word's "Query Options"
dialog opens and you should be able to specify filters in there. If you say
Yes, you are plunged into MS Query.
However, by default, Word 2003 does not connect to Excel via ODBC - it uses
OLE DB. To connect using ODBC,
a. either the document was already set up that way,
b. or you chose ODBC in the additional "Confirm Data Source" dialog that
pops up when you select a data source if that option is selected in Word
Tools|Options|General,
c. or you connected via MS Query
d. or Word failed to connect using OLE DB, in which case it tries to use
ODBC instead,
e. (or perhaps another route I do not know of)
Your best bet in cases (a) to (c) is probably to connect via OLE DB (or DDE)
and try again.
Otherwise, I'm not sure what is going wrong, but I would try a very simple
test with feshly created Excel and Word test documents to see if you always
get the problem, or only sometimes.