Try updating the firmware/drivers for it via Dell's support site. It could be that it is simply out of date. If that doesn't work, report back to us.
Thanks for replying.
The update search states that the driver is up to date.
Uninstalling the driver (by changing the registry) and rebooting has not changed the problem.
The drive can read audio CD's
With a DVD it does a long search of the disc and then asks for a disc to be installed.
This is the same for all DVDs some of which have worked perfectly with this drive in the past.
Drive and computer are 18 months old.