Searching a drive with vb.net - vb.net

Question

I am making a program that searches your drive for an executable.
Private Sub Button1_Click_1(sender As Object, e As EventArgs) Handles Button1.Click
Dim di As New DirectoryInfo("C:\")
Dim files() As FileInfo
Dim a As Integer
Do While a = 0
Try
files = di.GetFiles("FileName.exe", SearchOption.AllDirectories)
Catch ex As UnauthorizedAccessException
End Try
If Not files Is Nothing Then
a = 1
End If
Loop
txt_Location.Text = files(0).FullName
End Sub
As soon as it hits the first UnauthorizedAccessException, it gets stuck in an infinite loop. How do I skip over the files that produce the exception?
EDIT:
This is what I have now:
Public Sub DirSearch(ByVal sDir As String)
Dim dir As String
Try
For Each dir In Directory.GetDirectories(sDir)
For Each file In Directory.GetFiles(dir, "Filename.exe")
ComboBox1.Items.Add(file)
Next
DirSearch(dir)
Next
Catch ex As Exception
Debug.WriteLine(ex.Message)
End Try
End Sub
Private Sub Button1_Click_1(sender As Object, e As EventArgs) Handles Button1.Click
DirSearch("C:\")
End Sub

Answer 1

You need recursion here which handles each folder.
EDIT: As requested by the OP, a little example:
Public Sub DirSearch(ByVal sDir As String)
Try
For Each dir as String In Directory.GetDirectories(sDir)
For Each file In Directory.GetFiles(dir, "yourfilename.exe")
lstFilesFound.Items.Add(file)
Next
DirSearch(dir)
Next
Catch ex As Exception
Debug.WriteLine(ex.Message)
End Try
End Sub
Also take a look at the following answers:
Looping through all directory's on the hard drive (VB.NET)
How to handle UnauthorizedAccessException when attempting to add files from location without permissions (C#)
Also note, if you have enough access rights, you could simplify your code to this:
Dim di as New DirectoryInfo()
Dim files = di.GetFiles("iexplore.exe", SearchOption.AllDirectories) 'already returns all files at once
And at last but not least:
Avoid having infinite loops. Like in your example, they can lead to broken code just because some circumstances aren't like you've expected them to be. Imagine your code has run on your PC and you deployed this software to a customer - horrible scenario. ;-)