Odd PageControl Tabbing problem.. Yuk

Hi,
I have a PageControl
With a few DbEdit boxes on it and Two buttons
The Idea is to click a startbutton Enter a Password then the user tabs
around makes changes to the record and then clicks the Post button to
Post the changes.

The Pagecontrol tab (which is called 'setup')s'  OnEnter event sets
the Post button's Enabled property to false.. Then the start button
sets the enabled property to true if the password is good.

Heres the problem...
While editing the user is able to tab up to the PageControls' tab I
believe this is triggering the OnEnter event AGAIN and then setting
the Enabled property back to false.. so the user can't post.
There is no TabStop Property for a pagecontrols' Tab.. so  I cant set
that to false.

Any Ideas?
thanks
Phil