I have the Hitachi GD2000 and the last year it just stopped reading DVD-R disks although it supports them. Is it a bitsetting issue, cleaning isssue, disk speed issue? How can i look for a solution to it?
Im sorry my mistake its the Hitachi GD7500 that i have not 2000. Is there anyone that can help?
Sorry if I can’t help you out with a definitive answer… 
This is a rather old drive and I think it’s on time to face it might be a laser lens failure.
Best recommendation I can give atm; get a new drive. 
can i check the status of the drive with an application?