System.Runtime.InteropServices.COMException (0x800706BE): The remote procedure call failed

When I try to open an Excel document I have this error

System.Runtime.InteropServices.COMException (0x800706BE): The remote procedure call failed.

I built an application for my company, it works fine on every computer but on my boss computer it stopped working when he the app has to open an Excel document.

I have tried to change the Permissions in Component Services but it didn't fix it.

I am working on Windows 7.

Excel.Application excelApp = new Microsoft.Office.Interop.Excel.Application();
            object missing = Type.Missing;
            Excel.Range xlRange;
            Excel.Sheets xlSheets = null;
            Excel.Worksheet xlSheet = null;
            Excel.Workbook xlWorkbook = null;


 xlWorkbook = excelApp.Workbooks.Open(filePath, missing, missing, missing,
                                               missing, missing, missing, missing, missing, missing, missing,
                                               missing, missing, missing, missing);