Using Sonic Foundry Vegas Audio 2.0 for years, and for years this problem has plagued the product.  When a 2-3 hour MP3 or WAV file has been loaded into Vegas, and I press the SPACEBAR button, often 5 seconds of nothing occurs (the program basically freezes), after which the following message pops up:
An error occurred while starting playback
An unexpected error has occurred.
I close the error message and press the SPACEBAR again, and the program plays the audio just fine.  This error message will appear every few minutes, every other SPACEBAR operation.