Alt key and TMainMenu

Hello,

Has anyone ever had the problem of pressing Alt on its own NOT highlight
'Form1's' MainMenu? ie. it gets input focus OK, but the rest of the
'message' seems to 'hang around' somewhere and another click (or whatever)
is required to get control back.

If I rebuild Form1 from scratch at design time - by creating a new one,
adding a TMainMenu and various other buttons, all is well. However, if I
then add a new Toolbar, for example, the above 'Alt' problem happens again.

TIA,
Quentin Pain.