enabling & disabling attached toolbar stops sheet selection

[Dreiding]

I've added an 'attached' toolbar to my workbook. The macros it calls is
behind a worksheet. The toolbar can be used from any worksheet, but only
operates on the worksheet the code resides in. All works well at this point.
I added code to enabler or disable the toolbar buttons when activating or
deactivating the worksheet respectively. All seems to also work well with
the following issue.

code used: (when activated, changed to False when deactivated)
Application.CommandBars("STS Toolbar").Controls(1).Enabled=True
Application.CommandBars("STS Toolbar").Controls(2).Enabled=True

When I first open the workbook, I cannot move from one tab to another via
the mouse click on the tab. However, the Ctrl-Page buttons work. The mouse
click tab selection returns if I:
1) go into VBA editor and click in any macro screen or
2)Ctrl-Page to the target worksheet, click/execute the toolbar buttons,
select a cell within the worksheet.

What did I do to temporarly disable the tab selection capability upon
initial loading?

Is this a feature of Excel 2003?

Thanks,
- Pat