I have a MacBook Pro with Mac OS X 10.7.5. I had been using my Thunderbolt port to attach my DVI monitor (an Acer). I had no problems until it seemed like I had to lift the Thunderbolt cable up a bit to get it to connect my monitor to my laptop. Eventually, the cable stopped working all together, so I purchased a new one. However, the new one isn't working either, which makes me think it may be the actual Thunderbolt port. Again, however, when I connect the monitor to my laptop, the screen flashes blue and the mouse can go off the screen, suggesting that it is recognizing the monitor. I also run Parallels, and Windows sometimes sees that my Acer is plugged in. I really have no idea what to do next. Help is appreciated!