SMPlayer hang-up in 10 minutes if display is off

[Tokushima]

I use SMplayer to play audio files (aac, mp3, ...) not only video files.
I sometimes do it while doing other things like cleaning room, cooking food.
Display is not needed while audio files are only played.
So I want to turn display off while audio files are played.
You can find many small free software on web to turn display off immediately.
If I make display turn off by using one of the above soft, SMPlayer always hang-up in 10 minutes.

I set the internal HDD is turned off in 10 minutes by using "power option - control panel".

I guess that SMPlayer hang-up because internal HDD is turned off.

My desktop PC:
smplayer-0.8.6.5985-x64
Windows7 Professional 64bit
8GB RAM
500GB HDD