Play all seems to skip the first half my music list

My first week I had 33 songs on my Clip+ and it worked fine. Then I loaded 200 more and now when I go music > play all, I watch the first 95 songs scrolling rapidly by on my display, as if its processing their names. Then it stops on 95 and starts playing. If I manually forward through to the last song with the idea of circling back around to 1, the player again reads fast forward to 95. 

I use a Mac and I have loaded my songs by dragging folders for each Album into the SanDisk music folder. All music files are mp3. Are there some rules about how the folders and mp3 files are supposed to be named? 

Any ideas would be appreciated. It would be easy enough to remove all the songs and put them all back on according to some rules, if I knew what those rules were.

thanks in advance for your advice.