I have a suggestion uses the commands SQL to bring the result of his/her filter
Ex.:

TABLE: NAMES

FIELDS: NAME, ADDRESS, CITY

SET TO FILTER names.name = "RUSSELL" ---- NOT USED

WITH COMMAND SQL

SELECT name, address, city ...
WHERE name = "Russell"
INTO CURSOR tmpNames

In I begin him/it of his/her ´grid´ puts in ´RecordSource´ the name of the temporary table and it generates in ´load´ it ´select´ with all the data, before doing the filter, and in the moment of selecting ´combobox´ it executes ´select´ again .

Att.: Look commands down.

COMBOBOX1.CLICK


THISFORM.grdMatricula.RecordSource = ""

SELECT ...

THISFORM.grdMatricula.RecordSource = "tmpNames"
THISFORM.Refresh