The .wav file does play in Windows Media Player. I changed the ! to _ and received this new error:

Elapsed Time: 5230ms, block -1, trial 2, stim 2, Error 445, Object doesn't support this action, on line 640, during GoTrials of Form DDFullScreen
Subject 1, 9/23/2014, 12:04:06 PM, Finished. 1 Errors/Warnings.

Thank you for your continued help!