You may also be encountering problems based on the way you are shutting down your PS3. When you get impatient and can't wait, are you pressing the power button once on the front, or are you flipping the switch on the back?

You need to press the power button once - the system should beep a few times and then shut itself down after 5-10 seconds.

Shutting down your PS3 improperly will lead to corruption of files.

If the problem persists, replace the drive. Beyond that, it may just be a hardware issue that has developed.