Hey, A few days ago I upgraded the hard drive in my MBP (3, 1: mid 2007, 2.4Ghz) to a Seagate Momentus Gforce 500GB. I restored my system from a time machine backup and everything was running fine. Last night the OS entered a weird state where I couldn't force quit anything, or interact with any of the apps, yet could drag the windows around. The same thing happened again this morning. I installed the latest software updates (graphics driver fixes, security fix and iLife update) while I did a disk utility check, which came up fine. I rebooted and got to the login screen, but couldn't click on a name. Then I rebooted and now it won't reach the login screen, it just cycles between a blue screen and the default OS wallpaper with a mouse cursor. I've tried running disk utility, repairing permissions, doing a hardware test and flashing the PRAM. All diagnostics come up fine, including the HD and RAM. What is the likely problem? - new HD? - software updates? - problem when restoring from time machine? Is there anything else I can try before I restore from Time Machine again? Is it worth doing a clean install and migrating my old system over manually?