Simple User Form Macro Runs Very Slow for Some Users

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Hello,

I have a problem with a simple macro that launches a user form before saving that is running very slowly for some users.

'Code to reset the workbook view back to a default setting
    
    Application.ScreenUpdating = False
        
    Sheets("Regulatory CEs").Select
        
    ActiveWindow.FreezePanes = False
        
    Range("K10").Select
    ActiveWindow.FreezePanes = True
        
    Range("C1").EntireColumn.Hidden = True
    Range("D1").EntireColumn.Hidden = True
    Range("E1").EntireColumn.Hidden = True
        
    Range("A1").EntireColumn.Hidden = False
    Range("B1").EntireColumn.Hidden = False
    Range("F1").EntireColumn.Hidden = False


    'Code to launch userform that will capture approval information
    
    With frmApproval
        .StartUpPosition = 0
        .Left = Application.Left + (0.5 * Application.Width) - (0.5 * .Width)
        .Top = Application.Top + (0.5 * Application.Height) - (0.5 * .Height)
        .Show
    End With
    
    
    Application.ScreenUpdating = True

For some reason, it takes some systems 10-15 minutes to display the user form. Also, apparently this problem does not occur the user opens Word first.

I am using Excel 2007, and they are on 2013. Thoughts?