I have had a new rewriter installed recently.I have tried to use the full erase DVD on Nero but the D: drive is greyed out and inaccessible.
Try uninstalling the drive. My Computer > Properties > Hardware > Device Manager > Click on DVD/CD ROM Drives, highlight the drive and uninstall then reboot. This lets Windows detect and reinstall the drive.
When you ran Nero info Tool did you look at 'Configuration' to check to see if DMA is on? If the drive is shown on an IDE channel and DMA is off uninstall the appropriate controller and reboot. My Computer > Properties > Hardware > Device Manager > choose IDE controllers and uninstall the Primary or Secondary as appropriate. Check the PC bios to verify the drive is listed. And to confirm it's a Nero problem download and run IMGBurn. Tools > Drive > Erase Disk. http://www.imgburn.com/