This simple command crashes Micro Python on my board:

Micro Python build dddf5bd-dirty on 2014-05-01; Myriad2 with STM32F405RG
Type "help()" for more information.
>>> a=pyb.Pin('A7',pyb.Pin.OUT_PP)

to set pin A7 as a push-pull output. Crash also happens typing pyb.Pin('A7',pyb.Pin.OUT_PP) without the assignment. Same thing happens for B3, haven't tried other pins (these pins are relevant on my board) or setting pins as inputs, will try that next.
I think this is the first time that I tried to do anything with GPIO's since the API changed from 'gpio' to 'Pin.' Previously I had no issues using the gpio functions to set pins as inputs or outputs. Any thoughts?