New Songs Won't Play On SD Card?

I HAVE AN ISSUE WITH MY SDHC CARD, ALL THE MANY OF MY TRACKS ARE COMING UP WITH FILE IS DAMAGED WHILE SOME OF THEM ARE PLAYING. 

I have tried buying a new SDHC. I had a very old SD MMC type card before all this issue which worked fine but only had 32mb, couldnt play that many songs. Now bought  SDHC 32Gb card which only plays MP3 which is great more songs. No other codecs work as i have checked. I have converted every track to mp3 in i tunes 192 kbps. I do not have a format option fat 32 so i had formated to MS-DOS (FAT) as i have a mac. i have tried from as many as 100 music tracks to just 1. each one creates a shadow file on the original. or simply the track just does not work as says file is damaged when i load it into the Audi car media player SD card slot reader.    

I am at a complete loss. please can someone help me.