Toshiba Black Screen Inverter?

Hi there Guys I have a problem with my Toshiba A100 Equium. The screen strated to make a strange screeching noise from where the inverter should be located at center bottom of screen and then it goes blank. I am only a normal civi with computers but I was thinking how can the screen go back to being perfectly fine when I go to the switch users option in start menu when it goes black ? Would the screen not just be completely inoperable if the inverter failed? Could this be some sort of virus or other clash or is it only that I must get a new inverter, would realy appreciate your wisdom here fellas.