Well honestly I'm not to fond of the SendKeys approach. If all you're trying to accomplish is to show the start menu then I would suggest trying this.
Code:
Private Declare Sub keybd_event Lib "user32.dll" (ByVal bVk As IntPtr, ByVal bScan As IntPtr, ByVal dwFlags As IntPtr, ByVal dwExtraInfo As IntPtr)
Private Const VK_STARTKEY = &H5B
Private Const KEYEVENTF_KEYUP = &H2
Private Const KEYEVENTF_KEYDOWN = &H0
Private Sub Button1_Click( ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Call keybd_event(VK_STARTKEY, 0, KEYEVENTF_KEYDOWN , 0)
Call keybd_event(VK_STARTKEY, 0, KEYEVENTF_KEYUP, 0)
End Sub
Either way I'm sure this code snippet can be easily modified to suit your needs.