Transferring Data to Seagate External Hard Drive causes Finder to Freeze.

I have a mid 2010 Macbook Pro with Core 2 Duo Processor. It has 6 GB of RAM, with Snow Leopard as the original OS.
I also have two Seagate External Hard Drives, 3TB each.
I waited until a couple of days ago to upgrade Snow Leopard to Yosemite. Naturally the upgrade didn't go fluidly, so I did a complete restore from the recovery partition. This fixed all of the issues except one! I cannot transfer data to my two Seagate external hard drives.
To assure that Yosemite wasn't corrupted during the initial download and caused a corrupted recovery partition, I performed a restore from a Yosemite flash drive made elsewhere. The OS seems to be fine.
I have wiped the HDD and verified the HDD. It is of course in Mac OS Journaled format.
My first (Backup) External was completely wiped. Before and after, the format was and is Mac OS Journaled. It was my Time Machine Drive. I discovered the problem initially when attempting a time machine backup.
I tried my second Seagate external (Which is Fat32.) Even transfers far under 1GB, it was having the same issues. This verified the issue isn't a physical issue with the external drive.
I have no issue transferring data to the computer itself. It is only when transferring to the external.
Finder will first stop the transfer. It then will freeze and get the pin wheel. If you wait long enough, the screen will go white. You'll have to reboot the computer, and it will come up with a notification about the forced shut down.
I understand that Seagate externals originally had read errors with Yosemite. They read fine, the issue is only transferring the data.

Please help! I would greatly appreciate it. Worst comes to worst I can always go back to Snow Leopard, but there are a lot of cool functions I enjoy about Yosemite, and Snow Leopard is on its last leg for people supporting it with newer software.