Hi, I am new to Mac's and have a macbook 13" which was ex-display and had a couple of issues. It had a dodgy battery, which has been replaced and that sorted some of my problems. However, I still have an issue with the macbook shutting down on boot-up. It generally will run ok for a while, then at no particular time and for no particular reson, it switches itself off again. I have read something about the SMC flashing. My version is 1.4f8. I am beginning to think it is more like a hardware problem. The unit is out of warranty but Apple replaced the battery for free, should they be obliged to replace the other parts too if it hardware related? Thanks in advance.