I upgraded the hard drive of my MacBook Pro to a Western Digital Caviar Blue 500GB yesterday. The installation went smoothly. I'm always very careful when working inside computers. I do it for a living, but primarily on PC's. Anyway, after getting back up and running with the MBP, I noticed that the keyboard illumination no longer works. The screen dimming works fine, though. I've tested it in multiple lighting situations. I can even put my hands over the speaker grills (the location of the light sensors) and the screen will dim on cue, but nothing is happening on the keyboard. I've double-checked the setting inside the System Preferences. I've checked and unchecked it. No help. I also installed Lab Tick, that I saw mentioned when others complained about their illumination not working. It also did not help me. Could there have been something I accidentally disconnected while installing the hard drive? Could it be a software issue? I'm running all updates, including 10.5.8 that was just released.