Sounds like you may need to Flash your writers Firmware. I’ve had the same probs with 2 old Writers over the years, and also had it with the Optiarc 16x DVD-Writer, where it will burn DVD’s but refuse to Read or Write CD’s.
I’ve had no problems whatsoever flashing are restoring the drives read/write functions before, but be aware, that it can go wrong and totally screw up the drives ability to read or write any blank media, but hey it’s screwed anyway, and even if it was under guarantee, NEC Engineers will only use the same method to repair your drive, and if they screw it up, then you’ll more then likely get a 2nd hand refurbished replica drive, so you’ve nothing to loose really :).
Below is the direct download link for the ND-3570a Firmware upgrade. Read through the Text before you decided on what to do.