'exemplo simples mas funciona
Private Sub Command1_Click()
Timer1.Interval = 1000
Timer1.Enabled = True
End Sub
Private Sub Timer1_Timer()
Dim valor As Double
valor = txtvalor.Text - 1
txtvalor.Text = valor
If valor = 0 Then
MsgBox "Tempo esgotado.", vbInformation, "Tempo"
Timer1.Enabled = False
End If
End Sub