Are you on Windows? There was a similar report a couple of days ago.

> On 13 Mar 2016, at 13:52, Thomas Heniart <heniart.thomas@gmail.com> wrote:
>
> I have a strange bug too with a fresh image just downloaded
>
> When I create a new method in a class, the shortcut to create a block expression (alt + shift + 5) does not work