This just happened to me as well. However, my rc = [-30]. It appeared when suspending my laptop. Odd thing is that the screensaver still works. I am using Ubuntu 14.04 on a 4,1 macbook. It had problems earlier today when trying to wake it; I had to reboot it. I have both MacOSX and Ubuntu on separate partitions while using rEFIt to chose between them. The grub menu still pops up when choosing Linux.
This just happened to me as well. However, my rc = [-30]. It appeared when suspending my laptop. Odd thing is that the screensaver still works. I am using Ubuntu 14.04 on a 4,1 macbook. It had problems earlier today when trying to wake it; I had to reboot it. I have both MacOSX and Ubuntu on separate partitions while using rEFIt to chose between them. The grub menu still pops up when choosing Linux.