Okay, slashes in macros do interesting things, so let's remove them from the equation.
For your menu macro, use this:
Then whatever the name of this menu is, find the corresponding MNL file. The file name will be <menuname>.mnl (regardless whether it's your own custom menu or the stock menu from AutoCAD - although I suggest using your own custom menu)
So for example if your menu is named "Company.cuix", then the MNL file we need will be named "Company.mnl".
If that file does not exist, create it using Notepad.
In that file add this lisp code
Code:
(defun my_temp ()
(startapp (strcat "Explorer /e," "c:\\temp"))
)
MNL files are loaded automatically when a menu file with the same name is loaded.
I have tested this here and it works.