This problem has started ever since i put a blue cathode tube in my pc! The first time i started up the pc i got a grey screen with a flashing curser at top but the screen was also full of '¬' signs. i turned off the cathode tube and powered up the pc no probs, then turned on the cathode and it was fine. restarted the computer and been fine ever since. tonight i opened up the case, screwed in a new hard disk but did not connect any of it, just docked the HD. turned on pc and grey screen back. tried the usual stuff and now the '¬' signs have been replaced with 'X'. even tried with cathode even connected to power just incase but no difference. any ideas please??