My problem is quite simple to explain. I have an external HDD (100 Gb size) using an USB interface. When I connect it to my laptop (Sony Vaio CR) with W7, it is somehow detected by the system... it appears in the "Safely remove hardware" application, it does appear under disk drives in the Device Manager, but it is not mounted at all (and no, it does not appear in the disk management application...)
It is a SATA hitachi disk perfectly recognised by XP. W7 does recognised an old ATA external disk I have.