I have a Toshiba Satellite L355D that would not detect the CD Rom in the BIOS although the Rom appeared to powered up and running. Before I found the real problem I put in a new CD-Rom which also failed to be detected. I finally traced the problem to a ribbon cable connector that was between the jack the CD Rom plugged into and the jack on the mother board. The ribbon cable plug at the MB had backed out and was only making the power connections to the Rom making the Rom appear to be operating. After seating the plug and adding some rubber cement to the sides of the plug and reassembling the LapTop the CD-Rom reappeared in the Bios and worked fine.