Hi, have same issue. after upgraded to win-7, my MATSHITA DVD RW UJ-875S is not recognized as DVD RW, just as CD-ROM.
looking at the optical drive properties general tab Location:Location 0, Channel 0, Target 0, Lun 0.
which i think is the problem.
The question is, does the drive work? If not, I would recommend updating the drivers for the device. If that does not work, try updating the firmware. Most of this I would assume can be found at your PC maker's website or Matshita's website.