Hi I have 2 GB of RAM in my mbp right now, but I just got two new stick of 2 GB's each. However, it's the weirdest thing! I tried them both in at once, and the mbp doesn't boot at ALL. However, if I use one of the old 1 GB sticks, and one of the new sticks (doesn't matter which one), it boots up fine! And, it recognizes the new memory! Right now it says 3 GB of memory. so why wouldn't the two new sticks work together? The new ones are both:2GB DDR2 PC2 6400 SODIMM Thanks!!