Long time reader but new poster. I\'ve been wrestling with this issue for an entire day and it\'s driving me nuts. After scouring this site and Google, I\'m still stuck.
You are invoking Start-Process with a cmdlet (copy-item) as its filepath argument instead of the filepath of an executable file.
Start-Process
sudo xcopy '.\standard_menu.ini' 'C:\Program Files (x86)\Opera\ui\';
will do the trick.