So that didn't work?

grid.mouseicon = loadpicture(c\winnt\cursors\size3_rm)

It might be your code that's wrong. You are missing a
colon acter C and you are missing the file extention after the file name. Try this code...

Code:
grid.mouseicon = loadpicture(c:\winnt\cursors\size3_rm.ico)
If that doesn't work, make sure you have the full pathname correct.