Flashing Rom always Bricks

Hi, I've had my Galaxy note since launch and have run a custom rom on in just as long. For the past few monthes when ever I flash a rom I get the emmc brick and have to repartition and really flash. Any one know why this is? I make sure to be on a safe kernel, even flashing stock through Odin does this. No matter how I flash, Odin or cwm, the phone emmcs and I have to repartition then reflash and it works again. At the moment I am running MIUI with jelly bean. The phone freezes occasionally and crashes over night when Ihave an alarm set. this is no fault of the rom as its done it on the past few. Any one got any ideas, what should I do?