DM365:Write several video files into SDHC card(32GB) and find error occured at the size of a little less than 4GB of total video files

We use a SDHC card(DM365 platform,linux kernel 2.6.32 with the SDHC patches,and DM365 can recoginize the card correctly) to store the video files each about 1GB size. The SDHC card is formatted in Windows with FAT32 and 32GB size.We find that the next video files will lose the video file header and will overwrite the previous file after about 4GB of  total video files in the SDHC card.Our algorithm is to overwrite the previous file after use up the capacity of SDHC card.The video file is the MPEG4 file compressed by DM365.

What may be the reason?

Thanks

Best regards,

James