When I opened Men's Cuts, I had to connect all these external devices to my Mac. I have been a plug and play user since my graphic design days. I do ok with hardware and I am the technical person in my household managing all the devices. Well, about two months, after I opened my salon, my music would intermittently disconnect from my Bluetooth & my computer screen would go black. My hardware was new and I thought it was odd that I had these things happening. Mac's do not have these issues. Luckily for me, I purchased the Applecare. I called them to troubleshoot over the phone. They did a great job except it was happening more frequently.
I must have called Applecare 3x in a 30 day period to fix this issue before heading off to their retail store at Crocker. I dreaded the thought of having to sit at Apple.I don't like the atmosphere at Apple .Rick, the business manager helped me with my computer. They tested my Mac and everything checked out ok. He suggested an Apple repair person go on-site, since ithe problem only occurred at my salon. He gave me the name of someone who works on Macs but doesn't not work for the Apple store.
Two days later, an Apple God showed up. After carefully testing everything, it turned out that I needed a USB that plugged into the wall. I had a $5.00 USB plugged directly into the hard drive that is used as an extension to the printer and devices. "I had no idea that there were plug in the wall USB Hubs." The problem occurring was that the devices were draining too much power away from my computer. WOW, who knew? I ran out to Staples to buy a new USB with a plug. & spent $30.00 . Then I reconnected everything . (printer, CC card machine, Bose, Camera & Monitor.) Men's Cuts has not had a problem since.Read this for more info:http://www.extremetech.com/computing/115251-how-usb-charging-works-or-how-to-avoid-blowing-up-your-smartphone