Hard Drive

• Most laptop hard drives consist of multiple internal rotating platters. If the platters are damaged, their rotation can become misaligned, causing them to grind or click against the inside of the drive.
  
  

Fans

• In a Travelmate 4150, a broken fan can cause symptoms like grinding noises.fan image by Antons Matvejevs from Fotolia.com
  
  Fans are necessary in many computers in order to dissipate heat. However, if the grille or axis of the fan is broken, these parts can rub up against the fan's blades, causing them to wear out quickly.
  
  

CD/DVD Drive

• When CDs or DVDs are loaded into a disk drive, the rotation of the discs allows for data to be read. However, if the spindle or other rotation mechanism within the drive fails, the misaligned pieces can rotate and grind against other components.