my dvd burner is a sony DW-U18A and a friend of mine bought a 10 pack tdk 16x dvd discs. the problem is when i put it in my burner it makes screeching sounds when i put it in and it doesn't load at all. my friend suggested that it was the lens is not clean and if i clean it, it should take out the problem. but im not sure if thats true but if it is then how do i clean it? or if its not the case what is the real problem behind it.