Im new to monitoring so i was testing few monitoring tools and I've had this problem with nagios, i downloaded the Nagios XI VM and im using virtualbox to run it and when i reach the GRUB i get this Error 16 : inconsistent file system structure, i have tried troubleshooting the problem but i haven't found any similar problem, I'd appreciate some help and thanks in advance.

I suspect it means what it says, and you'll need to boot a rescue disk of some sort to fsck the filesystem.

Either that, or you're using a kind of filesystem grub doesn't understand.