I have a 17" MacBook Pro 2,1 ~2006 model 2.33 Intel Processor, running Snow Leopard. A year ago I upgrade the ram to 4GB (though this model only recognizes 3GB), and upgraded the internal hard drive to a 500GB 7200rpm Seagate Momentus. Since April this year, I have had 3 ocassions where the Screensaver locks up, the only recovery is to power off by holding the power button down for a few seconds, which leads to me loosing my drive partition. Because of the way OS X is sucky about mount points, I have the entire 500GB partition as one volume. Up until last week, I treated this as a minor annoyance, as I have multiple time machine backups, and the reformat and restore works and is relatively quick. Aside from making me reluctant to travel with this laptop (luckily I have an Air as well, but that does not work for all my needs). On my most recent trip not only did the volume get corrupted, the machine did not recognize the drive, or any drives on the machine (incl. the dvd drive). Only after removing the drive completely, a combination of the boot up key sequences for resetting the machine, and booting off the cd, did I manage to get the machine to eventually recognize the hard drive. I am unable to determine if this is a faulty drive, or a faulty machine. I have run the Apple Hardware Diagnostics which give the all clear - I have nothing to stress test the drive, and I am running out of debug options and patience. Although this laptop is getting "long in the tooth", it still works like a champ (except when it crashes), and my only gripe being its weight. Any suggestions folks?