arduino mega2560 lost connection when docking.

i have problem with arduino when docking with controller board for 3d kossel printer.

alone arduino works fine, computer(win10) find it and connection is good.
tested plink code and it work nice.
problem comes when i connect adruino board to controller board and immediately windows plays disconnect sound and on arduino board "L" led goes dark.

any help for this?

thx.