Last night I installed 4GB RAM from Crucial. Once installed, it booted up fine and saw that it recognised the new 4 GB RAM. I ran some CPU intensive processes and really noticed the difference. However, I then retired to bed listening to the an internet radio station from my MBP, and it went to hibernate mode. I tried to get out of it but it wouldn't so I had to power off. I then couldn't power up my MBP :-( My heart could have stopped! The battery was flashing one green bar, so I resetted the Power Management for 5 seconds. This still didn't work so I put the original memory back in. I resetted the PM again but hold down the power button for 10 seconds. It worked! I managed to ressurect my MBP so it OK now with the original RAM. Is there something wrong with the memory or did I just needed to hold down the power button for more than 5 seconds to reset the PM? I'm tempted to try and install it again. Thanks, James.