I have an almost 3 year old MacBook Pro 17" 2.33GHz C2D. When on battery power, I can run the laptop for about 20 minutes and then it just powers off, as if I pressed the power button and held it. The level indicator on the battery itself shows 4 LEDs and the O/S, when plugged in and rebooted, shows, typically, around 73% to 75% battery power left. The system can (and does) run for eight or nine hours on A/C (at work) with no problems. Can this still be a battery issue? Also, I just added an Express Card e-SATA controller recently but it is not used at home or on battery, just at work. Is it just coincidence that these problems are happening together? When the e-SATA card is pulled, it no longer shows up as part of the system. Is it possible to be a battery issue when it never really dies? Like, maybe it is lacking the correct voltage? Thanks!