how to remove list of users (10 users) in the GAL

[ple]

Hi,
This is very a very interesting and annoying issue. When a user composes a new message, he clicks on the To button then an Informational window pops up saying that "Not all results were returned (too many results were found). Please be more specific in your search criteria." with an OK button. After he clicks the OK button, on the left hand screen, there are 10 users appear in this box.
How do we remove these users off this screen? If they cannot be removed, can we edit the list to make it longer or, perhaps, shorter?
Thanks in advance,
PL
RHAS5
ZCS5.0.16