I have a intel imac 24inch purchased in september 06 Today while using firefox the screen became all blue as if all the windows were selected. the mouse still worked but nothing else. So I restarted my imac and now I get these wierd lines, either vertical or horizontal. I have tried many of the techniques suggested, pvram, unplugging everything, fsck in single user mode (which said the disk was ok)...but still everytime I boot my computer the apple logo appears then it acts as if it is loading up, but instead a white screen remains. I have a feeling that the os loads ok, but that the white screen is superimposed on top, because the light will flash after a few minutes when the display is set to go to sleep. I also have an xp partition which also doesn't load, it goes to black then the display turns off Any help would be greatly appreciated?