I've heard of this occasionally being related to a bad mp3 audio track. Can you try it with different music?
Also, what platform (Mac/Windows) and version of OS are you using?
Using Windows 7 and I took the audio track off. Also, thought I might have corrupted photo so I tried to save one at a time with same problem.
Hmmm, no bright ideas here, except that you might want to try deleting your preferences file and restarting Lightroom.
It's found at C:\Users\[user name]\AppData\Roaming\Adobe\Lightroom\Preferences\Lightroom 5 Preferences.agprefs
You can exit LR, then delete or rename the file (to ".old" or something similar) and then restart Lightroom and see if that makes any difference.