Calendar resize

After installing a calendar into a spreadsheet following:
http://www.rondebruin.nl/calendar.htm

I have slightly modified the code to make the calendar appear to the right
and down a little from the cell, see below:

Private Sub Calendar1_Click()
ActiveCell.Value = CDbl(Calendar1.Value)
ActiveCell.NumberFormat = "dd/mm/yyyy"
ActiveCell.Select
End Sub

Private Sub Worksheet_SelectionChange(ByVal Target As Range)
If Target.Cells.Count > 1 Then Exit Sub
If Not Application.Intersect(Range("B4:B1100,C4:C1100,Q4:Q1100"),
Target) Is Nothing Then
Calendar1.Left = Target.Left + (Target.Width * 1.1)
Calendar1.Top = Target.Top + 30
Calendar1.Visible = True
' select Today's date in the Calendar
Calendar1.Value = Date
ElseIf Calendar1.Visible Then Calendar1.Visible = False
End If
End Sub

I have found that the calendar resizes itself, making it too small to use.
The file the calendar is in is accessed by several people and it almost seems
as soon as the file is saved and accessed by another the calendar changes
size.

Is there any way of locking the size of the calendar?