Cd Writer Not Burning Anything

I have a MITSUMI CR-48X5TE CD writer in HP desktop and it worked fine for almost 3 and a half years and all of a sudden it stop writing to my blank media discs. I receive an error message saying “underrun error”. What does that mean and do I have to purchase another CD writer?

Defragging your hard drive(s) might help as this error is because data cannot be supplied fast enough to the writer & a badly fragmented HD will cause this.