Mp3 to cd audio

hi there
After going through a load of the threads i was unable to find anything similar to the problem i am having.
The problem is this i have been copying cds for about 3 years now and had no trouble until recently when i bought a mp3/cd player for my car and also a mp3/cd player for the house. when i play audio cds in them after about 30 minutes a strange what can only be described as a scratching noise is heard in the background which eventually becomes louder and then eventually the music breaks up.
this only occurs with mp3 players and the same recordings are fine when used on my normal cd players.
the recordings are from a mp3 disc which i copy to audio cd
and i have tried a few types of media.
the software used is nero 6 and i have also tried winoncd 6 power edition
are there any suggestions for example software,cd media , a slower writing speed or changing the bit rate any help would be gratefully received.