How is the user selecting "all"? Are you using a union query for the combo?
For example, say you want to select a Country in your combo, and also offer 'all', you could set the combo's rowsource to something like:
SELECT Country
FROM myTable
UNION
SELECT "[All]" FROM myTable
ORDER BY Country
In your query, you could use as criteria:
Like Iif(Forms!myForm!myCombo="[All]","*",Forms!myForm!myCombo)
HTH
Max Hugen
Australia