I bought a pair of Buffalo HD-LB4 external hard drives. Like many external hard drives these days, they don't have an external power switch. Instead, they sense when they are connected to a powered computer. Unfortunately, that doesn't always work, and I'm now trying to figure out how to coax my new hard drives to turn on. I've tried unplugging and replugging in the power and data lines and plugging into different ports. Any suggestions?