I bought a Toshiba Satellite P755-S5390 back 1 week before Black Friday in 2011. Here is my problem: If I am using the laptop via AC power AND my battery is attached OR if I am using the system and I am on battery power only, the system will shut down for no apparent reason. No warnings; fan is not running to signify overheating or any other warnings. System just shuts down. Then I have to re-boot and select "Start windows normally." The only work around to this is to remove the battery and run on AC power only. This is ok most of the time, but it limits my mobility. This is a very frustrating issue. Has anyone else had this problem? It almost seems as if the battery and the laptop are incompatible, yet this is the battery that came attached to the laptop. Thanks for your help.