First time poster, big issue.

Created an XLSM file in Excel 2013 (32-bit) which will be customer's new invoice system. Everything works fine on my copy. When I send him my changes via email, everything again works fine for the customer who runs Office 2010 (32-bit Excel). However, if the customer makes any change to the file (even simply editing text), the file contains many errors upon reopening.

Most notably, on start up the customer receives 2 errors from the Workbook_Open event. These errors include:
-Run-time error '1004': Activate method of Worksheet class failed
-Run-time error '1004': Method 'Sheets' of object '_Global' failed

These errors only occur on the first load for the customer and will not reappear. However, my big issue seems to be that once these errors occur, formatting errors result that never get corrected. I have 200 rows within the worksheet that switch from hidden to visible depending on the size of the invoice. Within these hidden rows are Form Control buttons used to delete products existing on these rows. When these errors occur, the Form Control buttons will not follow rows that become visible. Instead all buttons located on hidden rows bunch together on the last visible row. Again, I cannot replicate any of these issues on my machine.

The code for the Workbook_Open event:

Private Sub Workbook_Open()
 Dim ctr As Integer
 
'Check Visiblity of UPDATE & SAVE button on Workbook_Open, if on C:/ hide
 If (Left(ThisWorkbook.FullName, 2) <> "C:") Then
    ThisWorkbook.Sheets("QUOTE").CommandButton9.Visible = True
 Else
    ThisWorkbook.Sheets("QUOTE").CommandButton9.Visible = False
 End If
 
'Protects workbook and all sheets but allows all Macros
 For ctr = 1 To ThisWorkbook.Sheets.Count
    ThisWorkbook.Sheets(ctr).Protect UserInterfaceonly:=True
 Next ctr
 
 ThisWorkbook.Protect Structure:=True
 
 ThisWorkbook.Sheets("QUOTE").Activate

End Sub
It almost seems like the Workbook_Open event is executing before the sheet is open and thus none of the references exist. Is there a conversion process Excel is going through from 2013 to 2010 on start up that may be causing the delay in loading the form? Is it a Protection issue since the customer is receiving the form via the internet? I am out of logical ideas.

Much confidential material exist in this workbook, so unfortunately I cannot post the entire workbook.


I know I did not provide much but thanks for any help that can be provided,

J.P.