I've got a MacBook Pro that was purchased in March of 2008. It is 2.5GHz machine with 2Gb of memory. It has been a very reliable machine with no problems to speak of... until this past week. If I am on battery power it will shut down without warning at 56% battery power or about 2 hours of use. It does this whether booted in Mac OS or Vista. Just shuts down cold and will not reboot unless you go to AC power. I've reset the SMC with no effect. I've searched the net and found similar problems back in late 2007 that were battery related. Anyone else have any suggestions before I spend the money for a new battery? The battery shows to have 97% of original capacity with about 50 cycles. Thanks.