Lite On 411s+In CD problem

I am experiencing the following problem with 411s and In CD:

  1. Using DWD+RW for storing pictures, files, etc.
  2. Majority of the time no problems with writing, deleting and rewriting.
  3. Some time receiving pop up box saying that I cannot write to the disk it is read only.
  4. Right clicking on the drive and looking in the properties: MRW (Mount Rainier ReWrite) read: YES, write: NO. But I was writing to the same disk couple of minutes ago!
    Please help.