I do not understand the problem with involving the operating system.
The problem is I don't have admin rights, and I don't want to delve into
that area

If, for some reason, you cannot do this, the Excel workbook containing
the VBA code msut be open when it needs to run. Are you assuming
that?

Yes, think I did say that in my posting's opening line:
I've got an excel file which will remain open in a PC which is left on
24x7.