I was having the same issue discussed here but found my solution was not with drivers or a USB 2.0 hub. I was attempting to flash it after hooking it up to my board. What I found is if the RX and TX pins were connected, the flashing would fail for larger programs, but it would work for small Blinky type programs. Once I disconnected the RX and TX, the problem went away.
@johnnycanuck - Choose the Old Bootloader option from the tools -> processor menu after selecting the board. The new IDE versions by default assume you're using a nano with the "new bootloader" (which is present on official nano's since the beginning of the year), unless you tell it otherwise. But clones almost universally still come with the "old bootloader".