Dear Rotekz,
In a way, you may be right to suggest it is for hardware reasons that your 3TB HDD is not recognised.
I think that if you are using the power provided via the USB socket it will be inadequate to drive such a large HDD. If you read my "First Impressions" you will see that I had no trouble with a 1TB Intenso, though I did cross my fingers trying it! It is a pity Humax are not more helpful in this as I am sure 9/10 users attach a HDD as their first move. The current available will meet the USB2 spec., I am sure but you need to know the requirements of your HDD as well. You may also notice that I formatted to NTFS before I attached the Intenso; this may have helped too! The Intenso comes with a special cable bearing two USB leads, so that both may be plugged into a receiver to draw the power from the two sockets - a neat trick which was unnecessary for me.
I hope this helps! And good luck. I am more than pleased with the HB not least because it seems bug-free. Regards. IAINB