How can I roll back my DVD Rom's firmaware?

I have a liteon dvd rom. I upgraded my dvd rom from psoa to pasob, but when I reboot, at the start of the computer, it says ATAPI not compatible. But when I am on windows it seems that it doesnt have problem. Its just I dont like the message at the start of the reboot. How can eliminate this problematic message at the startup of my computer when i reboot?