I have the luxury of owning 3 of the HP dvd940i drives. Two of them read commercially pressed DVD's flawlessy, while one is very fussy about reading commercially pressed DVD's. I had about decided that the one drive issue was caused by a hardware failure, until I happened across the many comments from others saying that they were having the same problem.
While I understand the comments that the LiteOn drives are great writers, but not good at reading, I found that statement to be a bit defeatist. Why should these drives write all these different formats, but fail to read a commercial DVD? That indicates a fault with the drive that should be fixed. So, given that, I went "investigatin'."
First, I used the Flash Utility from (codeguys.rpc1.org) and saved a copy of the EEPROM code, and the firmware from both the working and non-working drives. Then I downloaded Kprobe 2.5.2 and went looking at drive information.
I discovered that both of the working drives showed the following:
FlashROM Manufacturer ID: EF
FlashROM Device ID: 14
FlashROM Type: NEX(NX25P16)
The drive that was causing problems showed the following:
FlashROM Manufacturer ID: C2
FlashROM Device ID: 14
FlashROM Type: MXIC(MX25L1605)
All three drives listed the firmware revision as 3H23 (2006/09/02).
I also had identified one commercially pressed video DVD that would fail to read at all on the failing drive, but read perfectly on the other two. I used that my test source.
I obtained the latest firmware for the LiteOn LH-18A1H drive (version HL06). Using the Flash Utility, I flashed the failing drive with the HL06 firmware.
Next, I went to the Control Panel => System => Device Manager and uninstalled the failing drive. Then, I forced a rescan of hardware so that it would add the drive back in. This time (as expected) rather than seeing the drive as an HP dvd940i, it registered it as a LiteOn LH-18A1.
Last, I inserted the commercial DVD that was consistently failing, and voila!... the drive read the DVD perfectly.
I compared the drive information before and after the reflash using the Kprobe Drive Info function, as well as the DVD Info Pro information (from Roxio Easy Media Creator 9 suite), and other than for the firmware revisions, and the identification of the drive, I can find no other differences.
Before the flash update, Kprobe Drive Info reported the firmware revision as:
DVD Writer 940d
After the flash update, Kprope Drive Info reported the firmware revision as:
While I have not done extensive testing yet, the reflashed drive is now reading commercial DVD's without problems, and all other read and write functions appear to be working normally. I did reflash the drive with its original firmware, and tested again to see if the drive failed to read the commercial dvd (and it did fail.) I then reflashed the drive with the LiteOn firmware, and again tested it (and it read properly.) That confirms that the change in firmware corrected the issue.
For those of you encountering the "Commercial DVD Read Issue", you may want to download Kprobe and see if the FlashROM information reported is the same as that reported by the failing drive I have. If so, then I would tend to think that there is something in the FlashROM chip or EEPROM code used on these drives, or something in a specific batch of drives produced at a particular facility that may be at fault.
FYI... I did try flashing both the EEPROM code and firmware from the good drive to the failing drive. Once I did that, I got the blinking green light and the drive was toast. I reflashed the drive with the original EEPROM code and firmware, and it was back to the original symptoms. Then, I tried flashing the firmware (only) from the good drive to the failing drive. This made no change whatsoever. The drive still failed to read the commercial dvd I was using as a test source.
My best guess at this point is that there is some compatability issue between the MX25L1605 FlashROM used in the drive, the EEPROM code used on this drive, and the HP 3H23 firmware. Of course, I can't confirm this with just three drives to test. But I have my suspicions.
Hope you find this helpful. If you test this, and find that you have a drive with the same MX25L1605 FlashROM type, I'd be interested in hearing back if a flash to the LiteOn firmware resolves the read issues. If so, we can feed this info back to HP, and see if we can get an updated FW.
Other than this one issue, I love the dvd940i drives!