Memorex is made by Lite-on?? I didn't know that. So even at that , the disks recorded by the Memorex/lite-on still work! And some of those are fairly old. The only bad disks are the ones with physical damage. Or never worked because of a bad burn and were coasters when taken out of the burner. Not ever been a problem with coaster since I got a Lite-on, course I have a faster bigger system, and buffer under run protection the sony and Memorex did not have. Had to RMA the memorex because it died, The one I got back never had any problems. Brother n law has it now, still working though an older slower drive.
That's ok though, he's an older slower brother n law
I bought several 16x DVD-ROM drives for various projects a few months back. These drives would choke on nearly every burned CD I'd put in them. Some would work, but only after the drives tried to read them for about 30 seconds. Most other media wouldn't read at all.
If a firmware upgrade fixed your problem, that's good you got it fixed. All I was saying is you probably should not have had that problem in the first place. For what ever reason??
What would not work in your drives??
Your drives didn't read those disks, mine reads everything! Did they use a different firmware on your 16xdvd than on mine maybe? Maybe you got a beta firmware

Mine are exactly as they came out of the retail box, no upgrades. One drive I have had many months (maybe a year, lost track) and I have one I bought just a few months ago. I have bought and installed a few for friends too at various times. I've only used a dozen or so personally, but they have all worked flawlessly with my disks. I know any I have installed are straight from the box. Any already installed on a system by some-one else I can't say if it was out of the box or upgraded. Knowing the owners I would geuss straight out of the box. But none ever failed to play a good disk.
Mine have played every disk ever thrown at them and that is every type I know of and never a problem! I love to burn disks

I rip all the cd's my wife buys and burn them to Mp3 cds with tons of songs. She takes em to work and plays em in an Emerson MP3/CD player. She doesn't have to change a disk all night, they get trashed at work, I burn another. Never had one not play in the DVD drive.
Vcd's, data, disk copies, recordable, re-writeable, DVD -rw. I haven't burned a DVD-r yet, nothing I did as dvd I want to keep permenatly yet.
The ONLY DVD disk I ever could not play has been the Platinum Edition Snow White from Disney. I heard MS released some type of patch for the problem. I got around it by installing a patch that disabled macrovison detection for my Ati All in wonder video/capturecard. Now that disk plays on my system in the Lite-on DVD drive. So even that one disk was not a problem with the Lite-on drive but with the Disney DISK and the garbage copy protection on it!
Not many of my friends have burners, but I installed some Lite-on DVD 16x drives for them. Some of them had camcorder vhs tapes I captured and burned as VCDs, they can play those on their 16x DVD drives.
I'm sure out of the millions of drives they made there could be problems with some I haven't ran across in the few I played with. Maybe it's like the Norcent standalone DVD set top players, one model number has 3 versions of firmware, depends on the serial number you buy as to what it has.
But based on my experince with every disk of every type that I've made working correctly in many Lite-on 16x dvd drives, I would geuss an update should not be needed and that's why they don't have one
Although if it had to do with region codes I could see needing a patch. You can only change that supposedly 5 times then it locks, but that seems to be normal for most DVD players, even set tops although you can often find the code and set it to region zero for all regions.