I was getting the error in the title when trying to create a custom partitioning layout in Fedora 16. Apparently it needs this partition to boot off GPT labelled disks.
What you need to do is simply create a 1 MB "BIOS Boot" partition at the beginning then continue with your desired layout. br>
I hope Anaconda people will be able to make this error message more meaningful as all this GPT stuff is rather new for a lot of users. br>