A family of Microsoft spreadsheet software with tools for analyzing, charting, and communicating data.
I'm not certain I know why this is happening from shortcuts, and I checked the command line switches for Excel and I don't find one to explicitly open Excel in Full Screen mode. So I'm going to take a first stab with this recommendation:
Locate the file named Excel11.xlb on your system. On my system it is in
C:\Users\yourusername\AppData\Roaming\Microsoft\Excel
where "yourusername" is the user name you log into the system with (not your password).
Rename that file to something like Excel11.xlb.old The next time you open Excel, that file will be recreated, and hopefully having a new Excel11.xlb file will affect the way that files are opened from shortcuts.
After you've renamed the file, first try opening Excel by itself. Then shut it down and try opening one of your shortcuts to an Excel file and see if it works properly.
Let us know if this helps any or if it turned out to be a waste of time. There are one or two other things I can think of to try to fix things. Not necessarily sure that any of them will actually fix it for you.