Two most regularly used optical drives recently stopped recognizing data DVD's that were created on these machines. There is no issue with CD media. The affected machines still recognize commercial 'film' DVDs from the public library.
When attempting to recognize the media, the OS seems to completely bog down as explorer attempts to display the drive contents.
Once in a blue moon, explorer succeeds in displaying the inserted disk, or even a directory on the disk - but further attempts to access the drive result in explorer crashing.
Nero infotool and CDroller will also sometimes report presence and type of DVD - succesive running of tests usually report empty drives.
After disassembling and cleaning one drive, it allowed normal operation for a few minutes, but reverted to previous state after disk ejection and re-insertion.
They are both HT-LG brands, but are located in completely different PCs (PC-Chips homebrew and Lenovo ThinkCentre refurb), with different OS (W2K - W7pro)and different interconnection (IDE and SATA).
The Sony, TDK, Philips, Maxell DVD-R media , both blank and previously written, are recognizable on two other, less-frequently used machines in the lab, neither having HT-LG hardware.
Replacing the drives with similar types did not correct the problem.Replacement drives had other issues, which is why they were hanging around - sticky doors etc, but included one IDE drive purchased for this repair exercise)
All of the LG drives, original and replacements, have labels dated before 2010. The other PC's that still recognize the media have similar dates of manufacture, but are Sony or Matsushita branded.
Using the regular suggestions to manipulate the W7 operating system ( device manager, optical drivers, atapi drivers, disk management, registry upper/lower limits, sfc etc ) seem to have no effect.
I've not reinstalled Nero, and haven't (recently) reverted to a Windows restore point.'restoring' didn't work the first time, so I don't expect it to work a second time. That is a bit of a rabbit hole.
I have ordered (by snail delivery) some non-LG drive replacements as a last resort - but am still curious to know if this is a more widespread issue.
Using DVD media for physical data back-up or transport doesn't seem to be common these days - but I've had large USB memory go bad on me lately, too. I also back up the OS on a USB-connected HDD.
I'm discouraged by this experience with DVD media and hardware, for data.
RL