OSX won't boot after re-install Got the flashing folder of death.

Tried verifying, repairing the disk. No luck.

Restored from Time Machine. No luck.

Rebooted with Command-Option-P-R. No luck.

The drive as far as I can tell is working properly....

Reinstalled and it still won't boot off the hard drive. How can this be the install worked fine?

Even went as far as putting a bootable USB flash drive and it sees that.

I tried pressing the OPTION key on boot but it only sees the USB drive.

This is madness. How can OSX install on a drive BUT then fail to boot from it?

(I could understand if the drive was failing, but this makes no sense)

I can replace the drive but that seems silly and might not be the issue in the first place.
Sounds like the partitioning is damaged.  If you can boot from OS X on an external drive, use Disk Utility to "Repair Disk".  If that reports OK, the Repair the partition with the OS X installation.  

The particular kind of Mac might be helpful, and the OS versions.  

Also, for Intel Macs, the disk must be partitioned with GUID.  If its gotten to be Master Boot Record or Apple Partition, it won't see the disk as a boot source.