I have a dual-boot system partitioned on a 500Gb drive, 261Gb windows 7, 200Gb Ubuntu 11.10 and recently added Fedora 16 on 39Gb at the end of the hard drive. I have two other drives installed separately an 80Gb drive with Ubuntu 10.10 taking up the entire drive, and a 1TB drive storage. I am able to boot into Windows 7, Ubuntu 11.10, and Ubuntu 10.10, however, right now Fedora 16 is sitting on the 39Gb partition not showing up in the grub. I did not install the grub for Fedora 16, should I of, was not sure if it would mess up the system completely. Now do I uninstall Fedora 16 and reinstall it with Fedora's grub or edit the grub that I am currently using and if so how? I am ok with understanding computers but far from being an expert, so please explain thoughly and in a simple manner. Thank you!

Green793

You should edit your existing GRUB. How exactly you do that depends on which version of grub you are using. For grub 1 you need to edit /boot/grub/menu.lst (I think), for grub 2 /etc/grub.d/40_custom Then rebuild grub. I think Ubuntu should be able to detect RHEL with a program that generates menu.lst. But it's been a while since I used ubuntu so I am not entirely sure.

You may find that not installing grub caused anaconda (the Fedora installer) to also not install the kernel.
No, I'm not joking. It happened to me at about Fedora 14 or so.
I just had a look at a Mint system I have - os-prober found and recognised the Fedora system (F15 in this case). Looks like you might be in the same position as I was.
Might be best to just reinstall F16. Select the same partition for the root, and choose to install grub to the root partition. Then re-boot Ubuntu and run "sudo update-grub" - Fedora should get found, and you can then boot it.

What boot manager is in MBR ?
Grub 1, 2 or Windows bootmgr ?

Starting with 16, Fedora now will automatically detect any OS previously installed similar to how Debian and Ubuntu does. RE-install Fedora 16 on top and let it take over the boot MBR.