Conceptually, what you're wanting to do is make the directory control sensitive to a change the user makes in the drive control. Here's how I do it...
Private Sub Drive1_Change()
'Hand off the selected drive to the directories control...
Dir1.Path = Drive1.Drive
Me.Refresh
lstFiles.Path = Dir1.Path
Me.Refresh
End Sub
Private Sub Dir1_Change()
'Force a change in the directories control to cascade down
'to the files list...
lstFiles.Path = Dir1.Path
Me.Refresh
End Sub
The Me.Refresh is very important here as otherwise the change in the control's data will occur, but the user interface would not update.