There is a major problem with Gnome a screen resolution. Picking a different one from the
control panel basically trashes the installation because you lose your monitor with no way
(that I know of) to recover.
See ticket #10084
Setting a different resolution through xrandr (which does not perform consistently) may
save the session but on reboot you are at the same (white-out) screen.
Any idea before reflash?
Any specific file to change/delete to go back to normal resolution?
How do I switch to sugar from the console? (see if the problem is also there).
This is certainly a breaker if true.