USB Serial errors

[aztrix]

basically i use a USB serial number security function where the user must have the USB drive inserted into their machine for my app to load.

on my machine this functions perfectly within a timley manner (couple of seconds) both in reporting an error if the drive is missing or moving on if its present. However on a users/clients machine if the USB is missing the app does not crash but takes it sweet time to report the USB missing, and ultimatley the user gets jack of waiting for it so they alt+ctl+del out of my app.

am i missing something, is this a bad idea for security?? or am i able to excluded particular drives from the serial number scan like A: and C: etc to save time..........................???

my code looks like this

    If LicenseInfo.blnLoadNormal = True Then
        txtValidationKey.Visible = True
        Timer3.Enabled = False
          Dim X As Integer
          Dim Serial As Long
          Dim VName As String
          Dim FSName As String
          Dim ret As Integer
          For X = 0 To Drive1.ListCount - 1
              Serial = 0
              VName = String$(255, Chr$(0))
              FSName = String$(255, Chr$(0))
              GetVolumeInformation Drive1.List(X) & "\", VName, 255, Serial, 0, 0, FSName, 255
              If Serial = CorrectSerial Then
                  GoTo CorrectDriveInserted
              Else
                If Serial = VDMasterSerial Then
                    GoTo CorrectDriveInserted
                End If
              End If
          Next X
          'Correct usb drive wasnt found, tell them, then exit the sub
          ret = MsgBox("Please insert the correct Software Key and Restart the program", vbOKOnly, "Incorrect Software Key")
          End
    Else
        Timer3.Enabled = False
        Exit Sub
    End If

CorrectDriveInserted:
    LicenseInfo.strUSBDriveLetter = Drive1.List(X) 'this assigns the USB Key Drive letter to the Variable in mod LicenseInfo
    CheckUpdate

cheers