Computer detecting one Arduino but not the other

I originally started out with a personal Arduino and was using that which worked just fine with my computer. I brought home an Arduino from work to play with as well. I'm not sure at what point it happened but my personal Arduino isn't being detected by the computer anymore. When I plug it in it lights up, but Windows doesn't make the noise that detects a USB being plugged in. I'm not really sure what to do at this point. Any thoughts?

3 possibilities in the order of likelihood:

  1. The "other" Arduino has nothing to do with the first failing.
  2. You damaged the first one and didn't realize it.
  3. One of the boards has a FTDI chip on it, and you need to update your FTDI drivers.