In Windows-7 you can choose to "burn" a disc using them as a "flash" memory device. When the burn is complete, there is an "eject" function which, when "clicked", "prepares the disc for use on any computer". It takes about 15-seconds for this process and then the drive opens and the disc can be removed. At this point, it is possible to use the disc on another computer.
To add data, the disc is again placed in the drive and the process starts again. The disc "opens" and the contents of the disc can be viewed, extracted, etc. Also, at this point, you can add additional data to the disc. This was done. After the new data is "burned", you go through the "eject" functions again. At this point the drive opens and the disc can be removed supposedly ready to be used on other computers. It was at this point that the problems with the discs happened. Neither disc was functional after the "eject" procedure was followed. I have used discs as "flash drives" before, have added data, and so forth, without any problems using the computer that was involved and on my other 2-computers which use Windows-7. Why neither disc was able to be used after the second session is what the problem actually is.
After the first session the discs worked normally. After the second session they did not.