tsubishi Chemicals made a public announcement that their "CDR74SP50" (packaged in 50 spindle case) media package series is defective. This affects all media that shipped after 13 of April 2001. There seems to be a problem during playback (after writing the CD) and Mitsubishi has expressed an open apologie to users and agreed to exchange the defective media for free.
In order to identify if the media is defective you need to look in the inner circle of the media and see if there is the S1311HB...... or S1312HB...... pattern. If case you need extra support just email
Mitsubishi. We suspect this warning applies only for the Japanese people but in case you have the defective media (and you are outside Japan) contact Mitsubishi for more info.