I have had the "disk not formatted" message several times with my digital
photo group, as well. I THINK (just guessing) that it happens with
heavily recycled disks. I think they just wear out after awhile or
something. I have never had it happen on a new disk...only the recycled
ones. I try to remember to throw away a disk after filling it maybe 5
times. Maybe Sony can tell you why it's happening. If you do find out
what it was, please let us know.