Macro that should create csvs of all the sheets of a workbook doesn't work! help!

How about this one?

Option Explicit   'good programming practice

Sub Make_New_Books()

Dim w As Worksheet
Dim FileExtStr As String

Application.ScreenUpdating = False
Application.DisplayAlerts = False


On Error GoTo ErrorHandler  'error handling

'following is not used and therefore not needed
'FileExtStr = ".csv": FileFormatNum = 6

For Each w In ThisWorkbook.Worksheets
    
    w.Copy
    
    
    With ActiveWorkbook
        .SaveAs Filename:="C:\8350\8350_" & w.Name, FileFormat:=xlCSV
        .Close
    End With
Next w

'Normal exit - exit here if no error
ErrorExit:
    Application.DisplayAlerts = True
    Application.ScreenUpdating = True
    Exit Sub

'If error display them and then exit through above code to reset alerts and screenupdating
ErrorHandler:
    MsgBox Err.Number & ": " & Err.Description
    GoTo ErrorExit

End Sub

Please ensure that you have a directory named '8350' under C:\