[R.i.m.s.k.y.]

вывернулся

var FormInitialized : boolean;

function InitializeLanguageDialog(): Boolean;
begin
FormInitialized := false;
...
end;

procedure DeinitializeSetup();
begin
if (FormInitialized) then begin
BASS_DeInit; //
gdipShutdown
ShowWindow(StrToInt(ExpandConstant('{wizardhwnd}')), 0);
WizardForm.Hide;
Sleep(200);
ShowWindow(WizardForm.Handle,0);
UnloadSkin();
RF(ExpandConstant('{src}\!!!.txt'));
end;
end;


procedure InitializeWizard();
begin
FormInitialized := true;
...
end;