Do backup /etc/X11/xorg.conf examble xorg.back
Xorg.conf is place where is resolutoins you can use.Some distros resolution can change on fly >ctrl and alt and +/- (+up -down) not work in my 10.2. (X Killing works.)ctrl+alt+backspace.
Then try solve you videocard and what resolution you you screen can..I belive 1024*768.
#xorgconfig....in console it ask' mouse,keyb.country,,,,and you videocard and best..resolutions you want to use.
Don't try too high..if something goes wron kill X ctrl + alt + backspace..
I hope this help..Always best way to learn is to do it hardest way..You always can delete xorg.conf and copy you xorg.back back.
and sorry my english..
I have slaky 10.2 my both machine 2'PIII and t21 thinkpad..works fine..so I think it works in you sony too