Trouble playing sound through connected device...

We have been teaching American  Red Cross CPR/1st Aid classes using their digital presentation file, which opens in Adobe Acrobat Reader.  We have the file running through a laptop and we have that laptop connected to a TV so our students can see everything on a larger screen.  The video files embedded in the presentation file are also displayed on the TV with the audio playing through the TV speakers.

This setup has worked perfectly for the last few months, but today we could only get the sound to play through the laptop and I don't know why.  I checked for an Adobe Reader update, but it said that we had the newest version installed.  If we try to play any other audio or video files from the laptop, the sounds play through the TV speakers.  The sounds also play through the TV speakers if we stream any audio/video files from the Internet.

My only thought at this point is that the problem may be associated with a recent Adobe Reader Update, but that's only a shot in dark from me.  Any help would be greatly appreciated.

Thank you for your time.