Private Sub cmd_open_calculator_Click()
On Error GoTo Err_cmd_open_calculator_Click
Dim stAppName As String
stAppName = "C:\WINNT\system32\calc.exe"
Call Shell(stAppName, 1)
Exit_cmd_open_calculator_Click:
Exit Sub
Err_cmd_open_calculator_Click:
'handle error here
Resume Exit_cmd_open_calculator_Click
End Sub