unexplained error (conflict)

[bomz]

I divided my Transdent flash reprogramming to HD devices into 3 partition
512 fat16, 1024 fat16(fat32) and 2.5 G fat32 all partitions primary first active
I boot from first the pure ms dos 7.0 (from windows 98 it's see fat32 partitions), pure - IO.SYS + COMMAND.COM only. I can read first and third partition through plop driver but if try open second partition errors occurs. In the same time I may do copy from this partition with Acronis True Image for DOS - there is no errors in image. I can read it under bootit - other dos system. I can't find reason of it.
mystery