Did you try to set the SelectedPath before trying to open the FolderBrowserDialog?
Dim fbd = new FolderBrowserDialog()
fbd.SelectedPath = "your path variable"
if fbd.ShowDialog() = DialogResult.OK Then
string newPath = fbd.SelectedPath
.....
From MSDN FolderBrowserDialog.SelectedPath
If the SelectedPath property is set before showing the dialog box, the folder with this path will be the selected folder, as long as SelectedPath is set to an absolute path that is a subfolder of RootFolder (or more accurately, points to a subfolder of the shell namespace represented by RootFolder).