Simple shooter game program help

Hi i have made a shooter game where cars travel across the screen and when you shoot them your score goes up. I have two problems. 1 is that when I start the program all the cars follow eachother really closely and I want to distance them. 2 is that the game ends after a certain time limit and then a message box is displayed and it basically keeps appearing until you force close the program. Here is my basic code for moving the cars:

Private_Sub Timer1 
PictureBox1.Left = PictureBox1.Left + 100
Ect.
End Sub 

Then my message box code is as follows:

 
'This is the button you use to start the game and the timers are both enabled here
 Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Timer1.Enabled = True
        Timer2.Enabled = True
        Timer2.Interval = 1000
        Me.Alarmtime = Date.Now.AddMinutes(0.1)
        Me.Timer1.Start()
End Sub 

'This where the message box appears 
  Private Sub Timer2_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer2.Tick

        If Alarmtime <= Date.Now Then
            MessageBox.Show("Time's UP" & "Your Score is" & Label2.Text)
            Me.Timer1.Stop()
            Beep()


        End If


    End Sub

Thanks