Unable to boot G75VW after re-partitioning

[Rogmilo]

After recovery from a boot problem I managed to get the laptop up an running with all drivers.
Figured needed to repartion my secondary drive,I have two HDD (750GB each), and used mini tool to format and resize the secondary drive. I also used it to hide my recovery partition and change drive letter of all but the OS (C drive).

Happily rebooted to see that windows is loading files bar coming up which quickly ended with “Reboot and Select Boot device or Insert Boot Media in selected Boot device and press a key” message.

Need help to sort out and going to BIOS didnt help. I have not touched the BIOS config ever since i got this laptop.
But screen shots attached.

Not sure if ASUS G75VW come wit IDE or ACHI as I did accientally change and save.

Any help will be nice

[Rogmilo]

Good news.. Took out my secondary drive. Laptop booted with no issues.
Put it back and the same problem started. Formatted the second drive and ran a startup repair (which could not fix anything ) and rebooted normally to get back to my desktop.

Ensured that the second disk was also GPT now.Thanks for all the help and links Clintglm!

[Clintlgm]

Yes we always recommend to remove any disk other than the disk you want to install to. Just for the reason you found here. its best to format your 2nd drive with it connected VIA USB