USB Error -16 and -15 ??????

I just hooked up my 4K via usb (on the back) to my laptop so i can copy my samples to the internal harddisk.
But when it's busy copying i get an error: USB Error -16.
Then my laptop (W7) asks me if i disconnected my usb. In AkSys the mpc 4000 disappears like i indeed disconnected the 4K.

whut's up with that? I allready tried another usb cable but the problem reoccurs after retrying to copy files -> 4K.
Has anyone seen this before? I tried to google it, but i couldn't find anything relevant it seems.
thanks in advance....

peace!

Maybe i tried to move too much data at once? Could that be the issue?

No, it can't be that. I tried moving small packages and after the 100% in AkSys it just disconnects and i get error 15..

im getting a little afraid here.. I don't like it at all

I'm sorry for the mess in this thread, but i found the solution:

when you're moving only 1 directory at a time it works without error messages.


I'm a noob on the 4K (after years on the 2500) so i need to get accustomed to the work flow/methods


Peace