Bug#403325: Problem is related to not picking up the monitor horiz and vert refresh rates

[Alan Chandler <alan@chandlerfamily.org.uk>]

After adding HorizSync and VertRefresh options into the Monitor section 
of my xorg.conf file, the full resolution modes became available.

These were obviously being picked up automatically before, but now need 
to be specified.

Whether that is still a bug or not, I don't know. 
-- 
Alan Chandler
http://www.chandlerfamily.org.uk