im new to this game so i have no idea about it

so it started after i installed LFS(demo)
i did a dumb move and alt+tabbed out in fullscreen(b4 i knew there was window mode)
and now all text is replaced with squares
http://img461.imageshack.us/img461/7955/asdfdc4.png

i tried re-installing it but it doesnt work
i have a radeon 9600 vcard for info
if any1 knows or has an idea on how to fix this it wuld b appreciated to post it here, thx

You usually get that when the graphics card runs out of memory, or the graphics drivers screw up. Usually a reboot sorts it, believe it or not - unless there's a deeper, underlying problem with your system of course.