verificar existencia de diretório...

Esta classe usa API para localizar arquivos com ou sem 'wildcards' e os retorna num array. É bastante rápida e conta com eventos para ajudar a dar um feedback ao usuário do estado da procura.

Para testar crie um form e um class module e renomeie o class module cFindFile. No form crie um commandbutton, um listbox e 2 textboxes (Text1 é para a pasta inicial e text2 para o arquivo a ser achado)

Cole no class module

Option Explicit
'Class Written By:  GDuncan
'              On:  8/11/98
Private Declare Function FindMinFile Lib "kernel32" Alias "FindMinFileA" (ByVal lpFileName As String, lpFindFileData As WIN32_FIND_DATA) As Long
Private Declare Function FindNextFile Lib "kernel32" Alias "FindNextFileA" (ByVal hFindFile As Long, lpFindFileData As WIN32_FIND_DATA) As Long
Private Declare Function FindClose Lib "kernel32" (ByVal hFindFile As Long) As Long

Private Const MaxLFNPath = 260

Private Const INVALID_HANDLE_VALUE = -1
Private Const vbBackslash = ""
Private Const vbAllFiles = "*.*"
Private Const vbKeyDot = 46
Private Type FILETIME
  dwLowDateTime As Long
  dwHighDateTime As Long
End Type

Private Type WIN32_FIND_DATA
  dwFileAttributes As Long
  ftCreationTime As FILETIME
  ftMaxAccessTime As FILETIME
  ftMaxWriteTime As FILETIME
  nFileSizeHigh As Long
  nFileSizeLow As Long
  dwReserved0 As Long
  dwReserved1 As Long
  cFileName As String * MaxLFNPath
  cShortFileName As String * 14
End Type

Private WFD As WIN32_FIND_DATA
Private hItem&
Private hFile&
Private msFileSpec        As String
Private msPath            As String
Private mbSearching       As Boolean
Private mbRecursive       As Boolean
Private mlRecursiveLevels As Long
Private mbUseFileSpec     As Boolean
Private mlTotalDirs       As Long
Private mlTotalFiles      As Long

Public Event BeginFindFiles()
Public Event EndFindFiles(FileCount As Long)
Public Event FoundFile(FileName As String, Cancel As Boolean)

Public Property Let Path(ByVal vData As String)
    msPath = vData
End Property

Public Property Get Path() As String
  Path = msPath
End Property

Public Property Let FileSpec(ByVal vData As String)
  msFileSpec = vData
End Property

Public Property Get FileSpec() As String
  FileSpec = msFileSpec
End Property

Private Property Let Searching(ByVal vData As Boolean)
    mbSearching = vData
End Property

Public Property Get Searching() As Boolean
    Searching = mbSearching
End Property

Public Function FindAll(FileListArray As Variant) As Boolean

  Dim asfiles() As String
  ReDim asfiles(0)
  On Error GoTo eop_error

  If FindFiles(asfiles()) Then
    FileListArray = asfiles()
    FindAll = True
  Else
    FindAll = False
  End If

eop_error:
  Select Case Err.Number
    Case Is > 0
      FindAll = False
      Err.Raise Err.Number, Err.Source, Err.Description, Err.HelpFile, Err.HelpContext
  End Select
eop_exit:

End Function

Private Property Let Recursive(ByVal vData As Boolean)
  'Future Property
  mbRecursive = vData
End Property

Private Property Get Recursive() As Boolean
  'Future Property
  FileSpec = mbRecursive
End Property

Private Property Let RecursiveLevels(ByVal vData As Long)
  'Future Property
  mlRecursiveLevels = vData
End Property

Private Property Get RecursiveLevels() As Long
  'Future Property
  FileSpec = mlRecursiveLevels
End Property

Private Function FindFiles(asFoundFiles() As String) As Boolean

  ' If we're running & we got a click, it's because DoEvents in
  ' either the SearchDirs() or SearchFileSpec() proc let it happen.
  ' Tell the proc to stop. Once SearchDirs() has un-recursed itself
  ' we'll finish off below where we left off...

  Dim drvbitmask&, maxpwr%, pwr%
  FindFiles = False
  If Searching Then
    Searching = False
    GoTo eop_exit
  End If
  On Error Resume Next

  ' A parsing routine could be implemented here for
  ' multiple file spec searches, i.e. "*.bmp,*.wmf", etc.
  ' See the MS KB article Q130860 for information on how
  ' FindMinFile() does not handle the "?" wildcard char correctly !!
  If Len(FileSpec) = 0 Then GoTo eop_exit

  If Len(Path) = 0 Then GoTo eop_exit

  mbSearching = True
  mbUseFileSpec = True

  RaiseEvent BeginFindFiles

  Call SearchDirs(Path, asFoundFiles())

  Searching = False
  mbUseFileSpec = False

  mlTotalFiles = UBound(asFoundFiles)
  RaiseEvent EndFindFiles(mlTotalFiles)

  FindFiles = True

eop_exit:

End Function

' This is were it all happens...

' You can use the values in returned in the
' WIN32_FIND_DATA structure to virtually obtain any
' information you want for a particular folder or group of files.

' This recursive procedure is similar to the Dir$ function
' example found in the VB3 help file...

Private Sub SearchDirs(CurPath$, asFoundFiles() As String) ' curpath$ is passed w/ trailing ""
  ' These can't be static!!! They must be
  ' re-allocated on each recursive call.
  Dim dirs%, dirbuf$(), i%

  ' This proc to be cancelled by the user.
  ' It's not necessary to have this in the loop
  ' below since the loop works so fast...
  DoEvents

  If Not Searching Then GoTo eop_exit

  ' This loop finds *every* subdir and file in the current dir
  hItem& = FindMinFile(CurPath$ & vbAllFiles, WFD)

  If hItem& <> INVALID_HANDLE_VALUE Then
    Do
      ' Tests for subdirs only...
      If (WFD.dwFileAttributes And vbDirectory) Then

        ' If not a  "." or ".." DOS subdir...
        If Asc(WFD.cFileName) <> vbKeyDot Then
          ' This is executed in the mnuFindFiles_Click()
          ' call though it isn't used...
          mlTotalDirs = mlTotalDirs + 1
          ' This is the heart of a recursive proc...
          ' Cache the subdirs of the current dir in the 1 based array.
          ' This proc calls itself below for each subdir cached in the array.
          ' (re-allocating the array only once every 10 itinerations improves speed)
          If (dirs% Mod 10) = 0 Then ReDim Preserve dirbuf$(dirs% + 10)
          dirs% = dirs% + 1
          dirbuf$(dirs%) = Left$(WFD.cFileName, InStr(WFD.cFileName, vbNullChar) - 1)
        End If

        ' File size and attribute tests can be used here, i.e:
        ' ElseIf (WFD.dwFileAttributes And vbHidden) = False Then  'etc...

        ' Get a total file count for mnuFolderInfo_Click()
      ElseIf Not mbUseFileSpec Then
        mlTotalFiles = mlTotalFiles + 1
      End If

    ' Get the next subdir or file
    Loop While FindNextFile(hItem&, WFD)

    ' Close the search handle
    Call FindClose(hItem&)

  End If
  ' When UseFileSpec% is set mnuFindFiles_Click(),
  ' SearchFileSpec() is called & each folder must be
  ' searched a second time.
  If mbUseFileSpec Then
    Call SearchFileSpec(CurPath$, asFoundFiles())
  End If

  ' Recursively call this proc & iterate through each subdir cached above.
  For i% = 1 To dirs%
    SearchDirs CurPath$ & dirbuf$(i%) & vbBackslash, asFoundFiles()
  Next i%
eop_exit:

End Sub

Private Sub SearchFileSpec(CurPath$, asFoundFiles() As String)
  'curpath$ is passed w/ trailing ""
  ' This procedure *only*  finds files in the
  ' current folder that match the FileSpec$
  Dim Cancel As Boolean
  Dim sTempFile As String
  hFile& = FindMinFile(CurPath$ & FileSpec, WFD)
  If hFile& <> INVALID_HANDLE_VALUE Then

    Do
      ' Use DoEvents here since we're loading a ListBox and
      ' there could be hundreds of files matching the FileSpec$
      DoEvents
      If Not mbSearching Then GoTo eop_exit

      ReDim Preserve asFoundFiles(UBound(asFoundFiles) + 1)
      sTempFile = CurPath$ & Left$(WFD.cFileName, InStr(WFD.cFileName, vbNullChar) - 1)
      asFoundFiles(UBound(asFoundFiles)) = sTempFile

      Cancel = False
      RaiseEvent FoundFile(sTempFile, Cancel)
      mbSearching = Not Cancel

      ' Get the next file matching the FileSpec$
    Loop While FindNextFile(hFile&, WFD)
    ' Close the search handle
    Call FindClose(hFile&)
  End If

eop_exit:

End Sub

Cole no form

Dim WithEvents clsFind As CFindFile

Private Sub command1_click()

  Dim asfiles As Variant
  Dim lLoop As Long
  Dim lCount As Long
  Dim bResult As Boolean

  Set clsFind = New CFindFile

  clsFind.Path = Text1          'UNC Paths are supported
  clsFind.FileSpec = Text2    'Wild Cards are also supported

  bResult = clsFind.FindAll(asfiles)

  If VarType(asfiles) = (vbArray + vbString) Then
    lCount = UBound(asfiles)
    For lLoop = 0 To lCount
      List1.AddItem asfiles(lLoop)
    Next lLoop
  End If
End Sub

Private Sub clsFind_BeginFindFiles()
  Me.Caption = "Começando"
End Sub

Private Sub clsFind_EndFindFiles(FileCount As Long)
  Me.Caption = "Achados " & CStr(FileCount) & " Arquivos"
End Sub

Private Sub clsFind_FoundFile(FileName As String, Cancel As Boolean)
  Me.Caption = "Achado: " & FileName

End Sub

fonte http://www.codex.com.br/colaboracao/VerOK.asp?ID=566