That could be a bad OS installation or incorrect boot device selected.
You should go into the BIOS setup and check the boot order and also if there is a device (HDD) available to boot from.
If there is an HDD available as first or second boot device (after dvd/cd), it is most likely the OS. You could use an install cd to boot from and select repair. It will check out the OS for any issues and continue to boot to the OS.
Final option is to re-install OS.