You really do not have to open the drive to clean it. First, as suggested, use canned air holding the can upright to prevent spraying freezing liquid. Eject the tray and spray the air in a sweeping motion ending up at one side to force dust out the other. Buy a lens cleaning disk from the store, it has a brush glued to a specific track position that will not touch the lens at all. The high speed that a disk spins causes the brush to gently blow the lens off and creates a static charge which releases the dust. If you have physically brushed the lens then you may have damaged it as its made with an extremely soft plastic. There are two lasers on a combo drive, one for the cd and one for the dvd. The cd laser is a little more forgiving as it reads a much larger burn mark on the disk. The dvd on the other hand achieves its larger capacity by using really tiny burn dots and its laser is really finicky. Try alternating cleaning with air and then cleaning with the disk, the disk will come with instructions on which track to play to make the brush and lens line up. The only other trick you can try would be to go into your Device manager and uninstall the drive and reboot. This causes Windows to reinstall the generic drivers it uses for optical drives and can eliminate the possibility of corrupted drivers. Since the drive will read cd's ok I would look into getting and external optical drive if portability is not an issue for you. If you need to move the thing around a lot, then replace the drive instead.