hmmmmmmmmmmmm
the only way i can think of doing that is by making the change event
NOT a change event, and calling it with an if-statement.....
well, no, i don't think that will work, either. because you can't use
any kind of an if-statement, because the change event will trigger
before the coding gets to the if-statement.
i don't think you can, once you've written it, without commenting it
out!

maybe you could make the change coding more variable with an if-
statement in it........
sub txtOne_change ()
if txtOne.value <>0 then
call my_real_change_sub
end if
so then if it doesn't meet your qualifications, it simply won't do
anything.
i don't know if this will have an effect on your project, though, for
speed or size issues, because it will trigger every time you make a
change in that txtbox, but maybe only fire occasionally. i've done
similar things before in worksheet_changes, & it doesn't seem to
effect anything, but they haven't been big involved projects.
hth!

susan