grub drops to command line on boot

[Herminio]

I installed Ubuntu-GNOME on my 2009 MacBook Pro. After reboot I get dropped into a grub command line. When I hit exit I boot into OS X. In order to boot into Ubuntu I need to hit the ALT button on reboot.

ProblemType: Bug
DistroRelease: Ubuntu 15.04
Package: grub (not installed)
ProcVersionSignature: Ubuntu 3.19.0-15.15-generic 3.19.3
Uname: Linux 3.19.0-15-generic x86_64
NonfreeKernelModules: nvidia wl
ApportVersion: 2.17.2-0ubuntu1
Architecture: amd64
CurrentDesktop: GNOME
Date: Mon May 18 00:07:41 2015
InstallationDate: Installed on 2015-05-18 (0 days ago)
InstallationMedia: Ubuntu-GNOME 15.04 "Vivid Vervet" - Release amd64 (20150422)
ProcEnviron:
 TERM=xterm
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: grub
UpgradeStatus: No upgrade log present (probably fresh install)

[Marcus Tomlinson (marcustomlinson)]

This release of Ubuntu is no longer receiving maintenance updates. If this is still an issue on a maintained version of Ubuntu please let us know.

[Launchpad Janitor (janitor)]

[Expired for grub2 (Ubuntu) because there has been no activity for 60 days.]