Using the DIR function may not be the best way to determine if a file exists, especially if you are using VB to compare two directories, and take actions when the files do not match.
Module
Function FileExist(sTestFile As String) As Boolean
'This function does not use DIR since it is possible that you might have
'been in the middle of running DIR against another directory in
'an attempt to match one directory against another.
'It does not handle wildcard characters
Dim lSize As Long
On Error Resume Next
'Preset length to -1 because files can be zero bytes in length
lSize = -1
'Get the length of the file
lSize = FileLen(sTestFile)
If lSize > -1 Then
FileExist = True
Else
FileExist = False
End If
End Function