Create a new project - just a form with a button on it.
Add this code.
VB Code:
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim i As Integer
Cursor.Current = Cursors.WaitCursor
For i = 1 To 20
f()
Next
Cursor.Current = Cursors.Default
End Sub
Private Sub f()
'Dim t As Date
't = Now
'Do
'Loop Until DateDiff(DateInterval.Second, t, Now) = 1
Debug.WriteLine(Now)
End Sub
When you click the button you will have the problem I think you are describing.
Uncomment the code at the start of Sub f() and click the button again.
Does this help?