that happened to me two years ago. i was so desperate, i opened the drive's cover (ASUS) and cleaned the lens manually with soft cloth and distilled water. it was risky but that's the only option left. the manual cleaning worked and it's still working perfectly in my kid's PC until now. a technician friend claimed some commercially available cleaners (brush and liquid) are even harmful to the lens, so i haven't used any such device in my CD/DVD R-W drives in the last two years.