Nvidia binary driver hang

Using a Dell Inspiron 15 7000 (nividia 750m / intel hybrid) while using the Nvidia 331 binary driver (both "tested" and "updates") Xorg hangs with syslog acpid: client <xorg> [0:0] disconnected.

when encountered, bailing out ot a console session and immedately returning to the graphics session resumes noramal operation. This condition is cyclical and reoccurs approximately each hour or less.

This condition is not encoutered after selecting the embedded intel video using the nvidia console.

This condition appear to be be present in 14.04 clean install. and was also present in 14.10 upgrade.