SongManager playlist limits?

Hi,

I prefer to play with the songmanager. Playing all my favorite songs or wannabees one by one without going to much to the keyboard.

But recently I noticed that, once I checked all my songs i wanted in the playlist, that the next day (or play through) some were back off.

Is there maybe a limit of how much songs you can add to the songmanager???

If so, how can I enlarge this?

thanks