Okay, here's the latest:
I got my fillet=0 button (the button I created) to work by using ^C^C_Fillet;r;0;Fillet. Apparently, AutoCAD was not returning to the fillet command to allow me to select the two objects to fillet. So, then I tried using the standard Fillet command on the command line. I entered "r" to change the radius and inputted 25 and then hit Enter. Guess what? The default fillet radius was changed but it did not prompt me to select any objects, ie., the command was ended and did not return to the fillet command. Strange. It never did that before I reloaded AutoCAD. Any ideas (or am I not making myself clear?)