It seems to be a bug in the wmi driver which affects acer-wmi when stack protection is enabled. Patch is available somewhere on the LKML and is waiting to go upstream.
...and here is the patch for all interested or affected http://patchwork.kernel.org/patch/29082/ -- Adrian C. (anrxc) | anrxc..sysphere.org | GPG ID: D20A0618 GPG FP: 02A5 628A D8EE 2A93 996E 929F D5CB 31B7 D20A 0618
