out of range

I have installed Debian Linux successfuly away from home, - on a CRT
monitor - complete with GNU etc. (full graphics i.e.) and when I took it
home it, it booted OK until I got to the "GNOM" displayer when my LCD
monitor went black displaying the message "out of range". I suppose, it's
to do with the monitor display setting, so I went back, but didn't know what
to change in the setting. I entered my correct monitor resolution, so what
else can be wrong?
Also, I don't know how to get out of the setting when when it's finished,
that is,
when the command promt comes up at the end of it?
Is this a common problem? Pls anyone? Thanks. Steve.