Excel after saving 10 files give me error - vba

Question

I have created one script which is launched on click button, so it loads CSV file from path and format and than save it. As I have files from 1...10000 so I made file like 1.txt and so on.
I am getting problem is when it start process everything goes fine but after 10-13 files it give error and excel closes. Following are codes I am using. Please assist me where I am doing mistake. I think I am doing mistake in array I tried redim but but that one gives me same error. This is sub which I placed on my button to start process. As I have more than thousands files so please suggest me solution.
Sub WorkbooksLoop()
' get the list of filenames
Dim pageStart As Integer
Dim pageEnd As Integer
pageStart = CInt(Cells(3, "C").Value) ' getting from cell of excel sheet
pageEnd = CInt(Cells(4, "C").Value) ' getting from cell of excel sheet
Dim Filenames(44) As String ' variable I know there are 44 files
For j = pageStart To pageEnd
Filenames(j) = CStr(j) + ".txt"
Next j
On Error GoTo NoFilenames
Dim controllerwb As Workbook
Set controllerwb = ActiveWorkbook
Dim wb As Workbook
Dim fname As Variant
Dim rootPath As String
rootPath = ThisWorkbook.Path
rootPath = rootPath & "\"
For Each fname In Filenames
' Make the controller active
controllerwb.Activate
On Error Resume Next
' If activate fails, then the workbook isn't open
Workbooks(fname).Activate
' If activate fails, then the workbook isn't open
If Err <> 0 Then
OpenFile (rootPath & fname)
Set wb = ActiveWorkbook
wb.Activate
' Otherwise, workbook is already open, refer to it by name
Else
OpenFile (rootPath & fname)
Set wb = ActiveWorkbook
End If
' do something to the open workbook my process to format sheet
deletingRowsColumns
ledgerSetup
resizeColumns
columnLines
columnAlignments
mergeTitles
settingNames
wb.Close
Next fname
NoFilenames:
End Sub

Answer 1

I have done everything and recode it in different way. But still after 10-20 files it through an error. As I was using windows machine on my mac as virtual machine, so I just thought why not i try it on mac with microsoft office. And have to change just forward slashes of directory to colon(interesting I thought it should be back slash but that is how vba was doing) and it worked I get alert of some file not saving, but it is ok at least I could do 1000 files easily rest I can save manually. But it realy work although vba engine is little bit slower in mac but who cares I just leave it for few hours to do all files for me.
Thanks for all your help. Mike yes I need to learn more about ActiveWorkbook and scripting. I will try to do as you told me but my work done. Thanks