[U-Boot] Error during NAND access

Hi, I have strange phenomena. I have DM365 baaed board. In some boards (Not all of them), I get this strange case: Accessing the NAND (Erase/write), like with saveenv command, followed by Ethernet access (TFTP/PING) stuck the SW. Accessing the NAND without prior access to ETHERNET works fine. I tried to debug this with TI code composer studio. When accessing the NAND, it seems that the CPUs data bus is hung, and I get the following message from code composer:

Warning:

0x40000020/-1032 @ marker 1022 Warning during: Execution,

The pipeline is stalled owing to 'data bus not ready' Did you ever encounter such a problem? Do you know if it is caused by HW problem (Corrupt NAND/DM365), or a fixable SW bug?

Thanks in advance Alex