OSX Problem: Jump and Run won't work

[owanomono]

Hi,

can't get the Jump and Run controls to work properly. When Laura's supposed to Jump she does some sort of sommersault. When she's supposed to Run, she doesn't but keeps on walking. This has got me stuck in her castle, where I can't cross a fiery chasm in front of a door. Really annoying. Of course I've tried the controls settings, but to no avail. She does what she does.

I'm on a Mac/OSX - no other problems so far.

Owanomono