External HDD Unmounted After Sleep I have the new iMac 21,5" and a Samsung G3 Station 1,5TB external HDD. When I plug my HDD, connecting to energy and via USB, no problems, Mac OS recognizes it and I can use it normally. The problem appears when I put my computer to sleep. When it wakes up, my HDD was unmounted and to use it again I have to remove USB cable and reinsert it. 
This is annoying me. I have looking for suggestions or improvements to put it work better, but no idea.
If you have any ideas, please let me know.

Additional Information: 


Snow Leopard 10.6.8;
On restart it works;
Disk utility cannot see HDD after it wakes up;
My HDD is formatted on NTFS. I don't know exactly, but it could be part of the issue. Unfortunatelly I can't format it to HFS+ or FAT32. My files and backup are all there.
If only we've searched before buying we would find this drive has this problems. It seems it lies either in firmware of enclosure or in firmware of a disk used inside. I didn't find FW updates for it on Samsung support site (but they have a habit to hide such stuff).

Probably, you may upgrade FW for the disk used inside enclosure and it could help but no guarantee.

If you can get your money back just do it because it seems this product is faulty (it probably behaves the same under Windows (you may try it if you could)).

If you can't get your money back or exchange it try this solution from MacOSXHints.