Problem with ADS Tech External case for DVD burner

i bought a Toshiba DVD burner and used it with the external case, the problem is when i am trying to burn it wont finish, it would sound like the usb disconnects and then connects again, what could be the problem??

Gonna need more info on this 1.

What motherboard have you got?
What model is the drive?
What Operating system have you got?

should be able to help you ones we know these 3 peices of info