Strange behaviour of "Call was rejected by callee." exception with Excel

I have an application that includes data exporting to Excel. And it works fine on most computers. However, there're two that throw

Call was rejected by callee. (Exception from HRESULT: 0x80010001 (RPC_E_CALL_REJECTED))

when I try to open Worksheet with get_item(). The funny thing is, when I set up breakpoints and execute everything string by string there are no exceptions whatsoever. Everything works fine and smooth. But in normal working behaviour, it just gives this exception.

MyApp = new Excel.Application();
MyApp.Visible = false;
string FileFullPath = Path.GetFullPath("Resources/Excel/FullMonthlyAct.xls");
MyBook = MyApp.Workbooks.Open(FileFullPath);
MySheet = (Excel.Worksheet)MyBook.Worksheets.get_Item(1); 
Excel.Range excelCell = MySheet.Cells[1, 1] as Excel.Range;

UPDATE: It's not a duplicate of the mentioned questions. There, most of the answers tell to check Office activation/installation/file assosiation. And as I've found out with the help of Hans Passant, i get this error simply because Excel can't load the workbook in time.

UPDATE: Solved Not the most elegant solution maybe, but it's possible to just wait till Excel opens the workbook as described in https://stackoverflow.com/a/54126361/1442373 by Joost.