I have a new Santa Rosa Macbook 13" 2.2 Intel. I purchased the Crucial 4GB (2x2GB memory set) as listed from their advisor. When I installed both chips, the Macbook will not boot. When I have one of the factory 512 MB chips installed along with either of the 2GB chips, it boots and recognizes the additional memory. I emailed Crucial and their response is below. Thank you for contacting sales and support. We are aware that this is happening and Apple is working on getting this resolved. This is compatible memory for your MacBook 2.2GHz Intel Core 2 Duo (13-inch White) MB062LL/B, so what I would suggest is using one 2GB module with one of your original memory to see if that temporarily works. You could contact Apple to see if they have any resolutions yet. If that works, we could do a return for the other 2GB module. Please let us know what you want to happen. Thank you. Is anyone aware of this issue? Is it a firmware problem? I purchased the Macbook 2 weeks ago from the Apple store. Is anyone else having problems with other brands of memory? I thought Crucial was one of the better brands, and it was slightly more expensive than the memory from OWC.