[ESS] error when activating R-mode

[Stephen Eglen]

> error still there.
>
> Backtrace: 
>
> ,----
> | Debugger entered--Lisp error: (invalid-function >
> with-silent-modifications)


What version of Emacs do you have?  What happens when you do 
C-h f with-silent-modifications

Is is actually a macro in Emacs 24.3.1 (and 23.3.1):

with-silent-modifications is a Lisp macro in `subr.el'.

(with-silent-modifications &rest BODY)