Cannot change Visible from OnShow or OnHide

I get the error "Cannot change Visible from OnShow or OnHide" under
the following condition.   I make a different form visible Form2->Visible =
true;
from the OnClick event of a RadioGroup.

Once the user deactivates that form I have the Deactivate event change the
ItemIndex of the original RadioGroup so we're no longer pointing at the item
that launched the other form.

If I step through with the de{*word*81}, I get a Click event after the
Deactivate event
and the ItemIndex of the RadioGroup is indeed changed and I take the new
path,
but then I get another Click event with the former ItemIndex set??? and this
then
occasions the error above.

Any ideas?
Dave Pariseau.