video mode not recognised

[norman]

Edubuntu has just been installed on to a new desktop PC. Installation
could not have been better and most hardware works including wireless.
However, when booting up or closing down a message appears on the screen
saying "video mode not recognised". Video and sound are on the
motherboard and I am able to hear and see but I am unable to set the
screen as I would like it. Google has not been much help so I turn to my
community members, please help.

Norman