So I have two w2072a monitors hooked up to my MacBook Pro. One is connected though a Thunderbolt to VGA adapter, and the other is from a USB to VGA adapter. The USB interface is not very good, but I usually only use it for textbooks. However since last night my USB monitor won't even turn on. I've restarted my mac, and it's still not working. The mac isn't even recognizing the USB. I've been using these monitors for almost a year. Any idea why it's not working?