Time machine stuck on "preparing"

I recently purchased a new back up harddrive (1TB Seagate) that is connected via USB-2. It is a USB 3, but claims it is compatible with USB 2 so not sure if that is an issue or not. It has backed up fine a few times, then it freezes on "preparing" for hours/days. If I press stop, it then freezes on "stopping". I have to unplug it, and then it it is fine for a few back-ups and then starts freezing again. Running 10.5.8

My old drive worked fine and never had this issue once. A google search indicates that this is a problem, but mostly when it is connected wirelessly.


Any suggestions on the issue?

Thanks

Jerryb