Ever been in front of the computer when suddenly the system locks up, crashes, resets or shuts off? Have you ever thought what causes these phenomenons besides Microsoft? The chances are that you experienced some type of power abnormality that your system simply couldn't handle. One way - actually the only way of preventing this from happening is to invest in a UPS (Uninterruptible Power Supply). They are designed to protect your system from power problems, and provide a limited battery backup, which will allow you to at least save your work and shut down your system safely. Today we're going to be checking out the Back-UPS Pro 650 from APC, the long-time king of the UPS world. It is a mid-ranged unit suited for the 'above average' computer user, who needs just that little bit extra…