Hi I have a problem,

I have recently got an acer xc600 and it had windows 8 on it, i then went an installed ubuntu over it, live mode works fine, install seems to go ok, and once it restarts this error comes up "ERROR: No boot disk has been detected or the disk has failed."
The HDD is a 2 tb drive and it can be seen in the bios fine.
I have checked that the partition is flagged as boot and such.

But i would really like to start with the basics because i need this up and running.

I would really appreciate any help, and i am open to all questions.

Thanks in advance.