I was getiing the same error too. If you save your file in matlab's default folder it won't happen. This is what I did.
Run matlab as administrator by default to store your file in matlab's default folder. (I had to do this because my default folder is in C drive)
type matlab in search window -> Open Location->right click->properties->Shortcut->Advanced-> Check run as administrator
type ballrepel0 in your command window. File->Save as. The location of the default folder is displayed here( There's probably an easier way to do this, but... I'm pretty new.. so this is what I did.)
Copy this location.
Now, save your file in this location.
I didn't get that error after doing this!