Hi, Our iMac 6,1 is failing to start. I have tried the following and am not sure what to do next. Any suggestions? 1) reset VRAM, no change 2) boot from original cd and run hardware test. No problems found 3) boot from original cd holding down c. Tries to load from cd then get message "you need to restart your computer. Hold down the power button for several seconds or press the restart button. After restart and booting from cd just get same message 4) boot and hold option key select to boot from external backup boot disk - apple logo and circle then white screen. 5) boot and hold shift key - tries to enter safe mode but just get a white screen with a blue mouse pointer in top corner Any help appreciated Andrew W.