I have Mac machine and I already installed Windows XP on the machine so it was dual boot and things were OK. Today I wanted to install Ubuntu on the machine so I booted from the USB flash and installed Ubuntu. At this time I have the following HD partitions:
1- 200GB for Mac OS X.
2- 300GB for Window XP.
3- 5GB for Swap.
4- 495GB for Ubuntu.

When I boot the machine it used to show the normal Ubuntu boot menu with all the operating systems, but only Ubuntu works! The other two operating systems give error and refuse to boot.

I booted the machine holding the ALT key and it booted normally into Mac OS X. I found out that After making the last two new partitions for Ubuntu the Mac is asking to format all the disk into one single partition. And now when I boot normally (without holding the ALT key) it takes me into OS X, and when I boot holding the ALT key as I want to select other operating system it shows only the Mac OS X partition and it does not show the other operating systems to boot from.

When I go to boot Camp, it says:"The startup disk cannot be partitioned or restored to a single partition.".

I need to fix this problem! I need all of the 3 operating systems.

Any idea?!