Trying to install Ubuntu 12.10, the Ubuntu installer does not recognize that a Windows partition exists. Looking around, it seems kind an usual problem, but with not many real solutions. Browsing around I found an utility to "fix"my partition table. My partition table was working great in Windows, so "fix" is more appropriate than fix.
Being myself I Windows person, I selected the Windows version of the program:
to run it I used
The first thing I got was:
NOTICE: GPT signatures detected on the disk, but no 0xEE protective partition!
The GPT signatures are probably left over from a previous partition table.
Do you want to delete them (if you answer 'Y', this will happen
Now I understood the problem. I used this disk to install MacOS, and the leftovers made the problem. I selected, Y (for yes) and then w to save and exit. Booted Windows again to see everything was OK, and then reran the Ubuntu installer. Now it recognizes my partitions. Now I might even try to install MacOS again, instead of Ubuntu.
The solution to this problem came from:
So if you do not understand what I did, maybe you will from there.