|Make sure the disk is clean and free of major scratches. Makes/models vary regarding their ability to read a scratched disk - e.g. LG drives are poor for that - Plextor drives are very good at that. . |
Your laser lens may be "dirty".
If this is a laptop, or a netbook computer that has a built in optical drive, eject the drive's tray, and with no disk on it, clean the obvious laser lens with a tissue or a soft cloth.
If you're using an external DVD drive, if it's a smaller "portable" drive that has no external power adapter, do the same thing.
If this is a desktop computer (or for any optical drive), use a laser lens cleaning CD in the drive. If you don't have one, most places that sell CDs and DVDs have them, or even some "dollar" stores have them for a buck or two.
If you're using an external DVD drive, if it's larger drive that has an external power adapter, use a laser lens cleaning CD in the drive.
Some burning or optical disk related software installs a "virtual" optical drive - the drive letter of it is usually of no use except for with the software (you have more optical drives in the operating system than you have physical optical drives).
It's created in more recent Nero versions that use a module called Imagedrive. E.g. Search for Imagedrive in this:
If you don't think you'll use Imagedrive, you may be able to un-install it in Add/Remove Programs if it's listed separately, and/or by changing something in Nero's configuration or Properties, and that will get rid of the virtual DVD drive and it's driver listing in Device Manager.