Eric,
I don't know why it behaves as you describe, it shouldn't because the fomr does not actually exist until its Init finishes and the listbox Init fires before the form's init even starts.
Here is what I would try before the gotfocus, in the form's load do;
Thisform.LockScreen = .T.
Do the population in the List's Init then in the fomr's Init as the very last line put;
Thisform.LockScreen = .F.
And see if that eliminates the problem.