Hi

A quick solution is to paste the following code replacing Userform1
with the name of your form in ThisWorkSheet.

Private Sub Workbook_Open()

Application.WindowState = xlMinimized
Load UserForm1
UserForm1.Show False

End Sub

Its does the job but you will have to see Excel start up then minimise.
Disabling ScreenUpdating won't do.

There are other ways to completely hide the Excel screen but it quite
complex (unless someone knows another way?)

Tom