I have a 2.2 GHz Macbook (I believe that makes it a "Santa Rosa") and tried to upgrade the memory to 4GB, however the macbook will not boot at all with 4GB in it. If I take out either one of the 2GB (I tried both configurations) modules and run the original 1GB with it, I'm fine and everthing shows that I'm running 4GB. But if I put them both in there, I get nothing. I bought the memory from Crucial (Micron). I'd greatly appreciate any help... Thanks!