Well, it all seems to be very sensitive. because of the fact that I had been testing with the various back-inputs and HdD's I hadn't noticed, but today I sent a couple of gig of tracks to my 500gig Lacie rikiki HDD attached to the BDP. In Finder on the Mac it went without problems, but then I had to update the BDP. It took minutes and minutes, and every now and then the HDD made a tsjirping sound. I feared the end of it...Tried to reboot twice, but to no avail.
Then I realized I had it attached to the upper USB port on the BDP. But because James told us 2 separate 500g's or even 750 below and 500 top should work like a charm, I thought no harm of it. Didn't work though. Then I switched to the lower USB-input, and voila, worked fine again.
Apparently the Lacie draws a lot of power, but without any of the front USB's loaded, it should have worked in the Top-Back USB I should have thought.
All the more reason for selfpowered drives? Too bad the BDP is so dependent on the right HDD. Would be really nice if this could be fixed without the need of a BDE....

Marius (taking back the new HDD to the store)
No I did not. I tried to use two drives, so need both inputs.