**System Information**
Ubuntu 12.04 (precise) 64-bit
Kernel Linux 3.2.0-61-generic
GNOME 3.4.2
(also tested on ubuntu 14.04 64bit, same result)
Graphics card: GeForce GTX 650 Ti BOOST
Nvidia driver version 331
**Blender Version**
Broken: 2.69, 2.70a & all daily builds up until 15May
**Short description of error**
layer management addon not showing up in N-panel
when pressing ruler - enable button in N-panel, blender crashes.