I've been dealing with HD issues on my mid-09 13" MBP for the past four months. First, I had my factory-spec 500GB drive fail in April after nearly two years of service. I was able to salvage everything, and bought a 2TB Western Digital external to store it all on. I have been backing up everything with it since then, so I have no worries in terms of data preservation. In May, I got a 500GB WD (WD5000BEVT, 5400RPM Scorpio Blue) from Newegg and installed it as a new internal. It partitioned and worked fine for nearly 3 months, when it failed a few weeks ago. So I get a WD Scorpio Black (WD5000BEKT, 7200RPM), try to install it, and I get "POSIX reports: The operation couldnt be completed. Cannot allocate memory" whenever I tried to partition it. I tried formatting it to NTFS on a WinXP install disc, it wouldn't even format from there. I also downgraded the EFI firmware from 1.7 to 1.6 in an attempt to get around a problem related to SATA II drives with 1.7, but that didn't work, so I suppose that wasn't the issue. It might have also been a mistake to do. I filed an RMA for the Scorpio Black, sent it back, got a 500GB Hitachi and it comes up with the same POSIX error. ...EXCEPT when I partition it from an external enclosure. That went smoothly. Is there something wrong with my SATA interface (NVidia MCP79 AHCI) that would have prevented the Scorpio Black from formatting, or the last two drives to fail? At the moment, I can't even update the firmware to 1.7 again, because it won't do so as long as I'm starting it up from my WD external's Snow Leopard boot. I'm going to try installing Lion to the Hitachi HD. I get the black screen issue with Snow Leopard now, otherwise I would already have installed it on there. If there's a problem with the SATA interface, then I cannot rule out the possibility that when I attempt to install the Lion-ready Hitachi HD into my MBP, it could fail to boot.