Can't boot into OS X after installing Linux & GRUB2

Hello everyone,

I have a computer with 3 operating systems: Mac OS X Lion, Windows 7, and Linux, in the order of where their partitions are located in my hard disk. Last week I reinstalled / upgraded Linux (Linux Mint, similar to Ubuntu) and now I can't boot into Mac OS X! The Apple logo and spinner appear but the OS never boots up, even after an hour.

I'm not sure if it's because when I reinstalled Linux, I installed GRUB2 (the most popular Linux boot loader) into space reserved for the recovery partition, or because I deleted the tiny partition between OS X and Windows.

Here's my current partition list:
EFI (FAT32) 200.00 MB
Macintosh HD (HFS+) 74.50 GB
UNALLOCATED 129.91 MB
BOOTCAMP (NTFS) 66.55 GB
Data (NTFS) 311.57 GB
Linux (ext4) 11.87 GB
LINUX-SWAP 977.00 MB
UNALLOCATED 1.02 MB

What should I do? I would prefer not to have to format my hard disk. I have at my disposal an OS X Snow Leopard DVD, a Linux DVD, and a Windows 7 DVD.

Looks like people who wrote similar threads about not being able to boot into OS X (but other OSes booting fine) got replies telling them to format the partition and reinstall OS X. I'd prefer not to do that!

Solution

I apparently used the Windows Disk Management tool to do some of the partitioning and that's the reason why the HFS+ partition was screwed up.

Okay, this is the way to solve it without reformatting and reinstalling everything.

https://discussions.apple.com/thread/2367608?start=0&tstart=0

Long story short, I needed to download the gdisk program which is a partitioning tool like fdisk that works with GPT disks.

I then ran gdisk from an administrator command line in Windows, and typed in "0:" when it prompted me for the disk.

gdisk will then report the partition table. If it doesn't list both a protective MBR and a GPT being present, then it's likely you chose the wrong disk. Try relaunching gdisk and typing in "1:"

Then you type "p" and look for the broken HFS+ partition and record its number. For my hard disk, it was partition 2.

Type "i" and then "2" (if necessary replace "2" with whatever partition number the last step gave). You'll see that the GUID code is wrong: it's probably listing the HFS+ partition as being Linux/Windows data, RAW, or something over than Apple HFS/HFS+

Now we type "t" and then "2", and then type "af00" to turn the partition back to the correct HFS+ type.

Type "i" and then "2" to make sure the partition is now an Apple HFS+ partition.

Now type "w" to write the new partition table. If you are lucky it will work, otherwise Linux and Windows will also stop working.