I started searching online for the fix, and it seems that Ubuntu changes the Darwin (default) bootloader to Grub on your internal disk, and OS X won't use it (at least not by default). Luckily, I have a bootable external drive with OS X on it, and I was able to boot into it by holding down the Option key (the primary partition still did not show up).
I ended up with the dreaded question mark folder when I tried to reboot my Mac, and nothing worked to boot into my OS X partition. I made the mistake of trying to use an Ubuntu 9.04 boot CD to install Ubuntu to an external (USB) drive on my Mac.ĭon't do this, unless you know the following: Regardless of the fact that you chose the external drive upon which to install Ubuntu, you won't be able to boot back into your Mac without changing the bootloader. This hint may be a bit esoteric, but I thought I was up for a long night of reinstallation pain before stumbling upon this fix. If your bootloader gets changed or corrupted, this fix will restore it without damage to your disk partitions.
