Doesn't boot, blue screen with patterns
After chime, apple logo and activity circle and it freezes in this state. or sometimes (maybe by pressed D button by startup) it changes the screen twice - clear blue to blue with small green patterns, with mouse in the left upper corner. I can move the mouse cursor but nothing more appears on the screen. sometimes the activity circle replace the cursor and I hear the HD working. I would like to fix the problem, any clues? Thanks
Is this a good question?