Audio on Mac Pro keeps cutting out?

I have a pretty new Mac Pro (not even six months old). I use it several hours a day, I do a lot of work with photos and videos. In the last two days, the sound will randomly cut out. To fix it, I have been going into my System Preferences and moving the volume around in the sound there (when it cuts out, doing this from the keyboard sound control does nothing) and it works again. This has happened maybe ten times in the last 36 hours. What could be going wrong here, and how can I fix it permenantely?

Not sure if this matters, but here are my specs:

Processor 3.33 GHz 6-Core Intel Xeon

Memory 32 GB 1333 MHz DDR3 ECC

Graphics ATI Radeon HD 5770 1024 MB

Software OS X 10.8.2 (12C60)

LED Cinema Display - 27-inch (2560 x 1440) - ATI Radeon HD 5770 1024 MB graphics

Any clues or tips would be greatly appreciated! Thanks so much!