I have bought about 25 DVD-RW (Ritek, 1X) and was able to burn successfully a handful of them (Still got 20 left)

Then I forgot about them, until I need to burn them again, my DVD writer (Pioneer A05) does not recognize the blank DVD-RW anymore !!! I can still burn 1X and 4X DVD-R disc, no problem at all. If I stick the blank DVD-RW in the writer, it spend about 1 minute in it then eject it out !!!

My config: Win2K, Pioneer A05, Nero to burn, 1.2Ghz Athlon, 256MB memory.

There is absolutely no config change between the time it works and the time it doesn't.

Any idea on this strange problem