Serial Chip Fried?

I bought my Arduino Uno R3 a few months ago. It's been working like a charm since then, but today, it stopped interfacing with my computer. Let me be more specific. I have a 2013 Macbook Pro Retina with OS X 10.9 (Mavericks). It has the latest Arduino IDE installed.

I was using it today and after uploading a simple sketch (it worked for a little while) my Mac stopped recognizing it, and since, I haven't been able to access it. The LED connected to Pin 13 stays on 100% of the time. The RX/TX LEDs don't flash, but the main functions of my sketch (other than the serial functions).

I have tried my other Windows computer, and another cable, just to rule out those possibilities.

Have I screwed my Arduino's Serial chip? What can I do?

Thanks!!