I've transferred several files over 1GB before, over USB. Maybe not quite as high as 1.5GB but certainly close. I had huge problems transferring with my old desktop machine, which I never got to the bottom of. I ended up using my laptop to do the transfer instead, no problems since then. I have a suspicion my problem was some sort of USB compatibility. So that's my suggestion - try transferring with a different computer... hth.
best regards,
stephen