Run Media Toolbox, select your drive, then click on
"Edit Partitions and Filesystems"
Click once on your boot partition and check to make
sure you have the "Bootable" switch selected.
Also, make sure the priority is higher than negative 128 too, it should be 0 by default.
Click "OK..", then click "Save to disk".
If that doesn't work, type the next line in the boot cli;
Protect s:Startup-Sequence +RWEDS
Then reboot....
