The actual message is not, strictly speaking, an error. It just means that you're bootstrapping the non-EFI way, and your machine's firmware does not adhere to a convention (I believe from DOS+Windows 95 and the 1990s) for marking "not an MBR virus and safe" firmware add-on disc device I/O handlers.
It's unlikely that F000:F0BF is actually unsafe, as that's in (notional) ROM.
This message is very likely a red herring.

