Page 4 - CD-ROM - Invalid MS-DOS function?

Recently, I have performed a system recover and set my computer back to factory conditions, and a while before I did that I made a backup of all my files using 3 DVDrs.

Now that I want to use them and recover the files, it seems that it won't work. At first, I can place the DVDs in the tray and try to run the application from the CD, that doesn't work, it gives me the error message : E:\Invalid Function.

So I thought maybe if I coppied all the files on the DVDs to my computer it may work then. I was still wrong and it's giving me the problem that everyone is having on this thread: Invalid MS-DOS Function.

I really hope someone can find a solution because I really don't want to lose all of my files as it will take a VERY long time to recreate them. A bit like someone else's problem I heard on here.

I've faced the "Invalid MS-DOS Function" error several times. I'ts a matter of bad media, bad burns, and/or bad DVD reader. AT least in most instances.

Did you perform a disc scan of the defective CDs/DVDs on Nero CD-DVD Speed? - you need a LiteOn or Benq burner to do this, or a Plextor using PlexTools instead of CD-DVD Speed.

I did this every time I found low level errors, like the one described, and each time the discs showed some (or many) C2/PIF errors (Parity Inner Failures), according to CD-DVD Speed (Disc Quality test).

It's a well known fact that CD-R/DVD-R discs that seem good or even perfect may have some "hidden" unrecoverable problem, due to some defect on the media or, most of times, to an erroneous burning. For instance, most media burns OK at certain speeds but becomes almost unreadable if burnt at too low or too high speeds.

Yes, even if burnt at very low speeds. Thus, "I always burn CDs/DVDs at the lowest possible speed" is not always a good behaviour. For instance, Verbatim Datasafe+ CDs (aka Crystal Super-AZO), MCC manufactured (not if TY manufactured!), if burnt at the lowest possible speed the burner allows (usually 4x), will have several C2 errors. These discs are known for burning correctly only between 8x and 32x - this on a recent burner, older burners, such as a 8x2x24x for instance, work rather differently.

The reason because in many cases the files work correctly if played from the CD/DVD but won't copy to the HDD is that removable media performs different error-checking procedures, that are somewhat "easy-going" if compared to those used by NTFS. For this reason, certain files (not all) can be copied to FAT32 partitions (those used by Win98) but not to NTFS partitions. We may simply state that NTFS doesn't accept these "crappy" files, while FAT32 does.

By the way, did you try to create a FAT32 partition on your Win2K/XP system, for instance using some unused HDD space, or by resizing existing NTFS partitions? In many cases you will notice that you are able to copy at least some of the defective files on these partitions...

Cheers.

^ what he said. I will have to try that FAT32 trick next time I run in to this. Does a usb stick formatted to FAT32 act the same way as the HDD in this situation?? Good tips, guy.

Another solution might be to try to slow down the reader's speed. CD/DVD readers always try to read discs at the highest possible speed (18x or whatever), to slow down if they encounter some problem. When reading at lower speeds, they can read somewhat better, and this might be enough for marginally bad - or marginally good - files, that are, so to say, "on the border".
However, as far as the reader BELIEVES he's reading correctly, he will continue to use the higher speed...
Time ago I noticed that if some crappy audio files are opened with CoolEdit 2000 or some other audio editing software, they are opened with no errors, at least in many cases (in other cases I found that some part of the audio track was missing, or that some part was repeated twice or more). By the way, CoolEdit always performs a low-speed reading of the files, slowing down the speed of the drive.
I don't know, however, how to force the drive to read at low speeds during a simple copy operation...

I have windows vista. Some of my disks have this problems, they are DVD+R's. I have 12 .AVI Files on one of the disks with this problem and only the first four would copy onto my desktop. I tried to copy the rest directly onto the C: drive and the fifth and sixth files worked while the rest still dont. First I tried with my burning drive, then with my regular dvd drive. The DVDRW drive progressed further then the regular dvd drive on the 7th file but neither copied the whole thing without the error.

could be just a bad disc, guy - happens with other discs?

yes, it happens with other discs. I dont think thats very relevant though. The fact that its more likely to copy to a file location thats closer to C: should give some kind of indication why it is doing that ms-dos invalid function thing.