I bought wd3200lpvx to substitute my dead hdd on my dell inspiron 1525. When I changed it I had the exact same problems. I tried changing BIOS settings, etc but nothing worked. Solution:: What worked is trying to put the HDD in the laptop without using the drawer/case where you put the disk before inserting it in the laptop. After several tries I managed to put it in the SATA (when I managed to put it, it couldn't move easily as it was attached to the SATA port). Then the HDD was detected normally. So the case is clearly the 9.5mm vs 7mm of height and there is no mechanical trigger. It's just that the 7mm height disks on the drawer won't attach to the SATA port. My doubt is if I should leave it like this (without screwing the disk though) or to buy another 9.5mm height disk.