Excel Home opens spontaneously

I have attached a file (MASTER09.xlsm) which I run to chart stock market symbols.  It ran OK with Excel 2016, when I could automatically step through as many as 16 symbols.  Now I have Office365. 

1. If I run a single symbol (UDOW.K) I can repeatedly close/reopen the file.
2. If I run 2 symbols, then close the file, Excel Home opens.
3. If I run 3 symbols, the macro aborts, closes the program, and Excel Home opens (usually).

Uninstall/Reinstall Office 365 did not fix the problem, and I have looked carefully at File/Options and Visual Basic macro setup.  The macro runs OK on another computer (back East).  Appreciate any suggestions.  Bill Roberts