I've actually had this problem for a while but I was ignoring the problem that I had.
I originally used 10.6.8 for a very long time and it worked fine but I needed to use an iB00t USB I built to boot into Snow Leopard because even after trying to install Chimera using MultiBea5t I would get the "Operating System Not Found" error.
I ignored this for all this time but now I'm looking to fix this as I installed 10.8.1 because now I only have Mac OS X on this HDD and nothing else. No other partitions or operating systems installed on the HDD I'm trying to boot from.
I have a HP DV9838ca. The HDD I'm using is a Toshiba MK2546GSX. I've already tried this fix but it didn't work.
Heres what I did to install Mountain Lion:
- Bought the Mountain Lion app
- Made the USB installer using UniBea5t - Mountain Lion (picked Laptop Support in the options)
- Formatted my HDD using Disk Utility to a GUID Partition table and the Mac OS Extended (Journaled) filesystem.
- Finished installing
- Restarted, booted into the setup window using the Unibea5t USB.
- Finished the basic Setup
- Ran Multibea5t 5.0.2
- The options I picked were, "##### Installation", "VoodooHDA 0.2.1", FakeSMC Plugin "Motherboard Plugins" "(Nvidia GeForce Plugin)", and "PS/2 Keyboard/Mice and Trackpads"
- Rebooted and got the "Operating System Not Found" error again
Thanks for any help.