I really do not know how Macs work. srs5694 had a Mac and knew gpt/hybrid partitions really well. I do not know if he will come back or not. I will post a link to srs5694 info on hybrid partitions.
I saw you clearly saying- "I really do not know Macs" in this thread, yet I know nobody better than you to seek help from (srs5694 doesn't seem very frequent on the forums).
If possible, please take a look at this thread: http://ubuntuforums.org/showthread.php?t=1923546
The OP seems to have the same GPT/Hybrid MBR issue that you have commented on a few times.
I've asked him for boot info results, but am not sure how to proceed after that.
Thanks and Best regards
Just noticed (while searching for one of your posts to quote) that you became a Staff Member. The only surprise it gave me is why it took so long!