It might be getting old and/or dusty. There's physical moving parts in there, and I doubt that of ALL the components in a PC, the CD-ROM is the best constructed, so maybe it's just getting worn out. I know my old 2x/8x CD-R (note the lack of a 'W') would sometimes have trouble reading a CD disk and would make strange noises. It almost sounded like the drive mechanism would get stuck on something and you'd hear the CD disk 'skid' on part of the drive.