Glitching USBs/cannot hold a connection

[tarinmart]

For quite a while now, whenever I connect my iPhone to my mac usb ports, the connection is extremely unstable. What I mean by this is that the phone will not charge for more than half a second, then reconnect, and the computer will not recognize the phone for long enough to do anything. The phone is constantly buzzing when I plug it in because of the charging notification. I've tried different cables and USB ports and the result is all the same, the computer cannot hold a connection with the phone even though they are plugged into each other. When my laptop is plugged into the USB port, it functions just fine. It seems to only be iPhones and their cables.