Mac desktops forum: Why can't I copy big files to new USB drive?

So, I have an existing 1.5GB Seagate Go-Flex Desk drive that I have been using as my Time Machine for some time. No problems, it just works.

This new 3.0TB Seagate Go-Flex Desk drive that is USB 3.0 and backwards compatible to USB 2.0, it just doesn't work. Here's the final straw for me.

Now that I have figured out how to Partition -- -- I partitioned BOTH my new 3.0TB and old 1.5TB Seagate drives.

I meticulously followed EXACTLY the same process for both. Both with GUID, both partitioned with all previous partitions deleted.

I set the old 1.5TB drive to be my Time Machine destination.

I attempted to copy a single 16.65 GB video file to the new 3.0TB drive while the Time Machine was running.

So, essentially, at the same time, I have disk copies running to both drives.

The Time Machine copy is still chugging away, over 49GB of data transferred to the old 1.5TB Seagate.

The disk copy to the new 3.0TB Seagate froze after 2 minutes and 2.11GB copied. Frozen. Unresponsive. Can't stop it. Once Time Machine finishes, I will reboot to kill the copy.

I have read multiple posts from Mac users complaining about Seagate drives, so I am now done with this Seagate and have already ordered a replacement Western Digital.

Many thanks to everyone for all the ideas, but my strong recommendation to anyone is: Don't buy Seagate USB 3.0/backwards-compatible USB 2.0 drives to use with your Macintosh on a USB 2.0 port.