VBA macro only works once.

So again it works the first time but crashes.

It seems that after it finds all the files and extracts from them it starts to attempt to do it to the zmaster file, which obviously causes problems.

Upon Re-opening I added a line I don't know is valid but worth a try

Do While Len(sFile)
        Debug.Print Now, sFile
        If LCase(sFile) <> LCase(ThisWorkbook.Name) Then
            Workbooks.Open (sFile)
            Range("A2:D3").Copy Sheet1.Cells(Rows.Count, "A").End(xlUp)(2)
            ActiveWorkbook.Close SaveChanges:=False
            sFile = Dir
        End If
    Loop
    Application.Stop (Now + TimeValue("0:00:05"))
End Sub

I went through the code one line at a time and it went down fine until I reached workbooks.open and then it gave the classic suppliers-a.xlsx cannot be found.