Songs don't shuffle properly

[aessof05]

So this happens mostly when on an artist playlist. I chose the artist playlist, and clicked on Shuffle. It will initially start off shuffling the first three or so songs, then afterwards it does not work. At one point, it plays the same song 4 times in a row. Often it just recycles the same 5 or so songs but jsut different version of it. 

For example, I was listening to Mumford and Sons and it played Believe, then it played Believe again, and then it played Believe Live version, then it went back to Believe, and then eventually another song. This is frustrating because it should be shuffling between the songs from the artist, not just the same 5 songs or playing the same song 3 times or more in a row. It is partiuclarly frustrating when the artist has about 4 albums but you only keep getting the same 5 songs. 

It has been happening for about 5 months now and I have no idea what it is or how to fix it. It is pointless listening to artist playlists now and I used to love the fact that I could play an artist I was fond of and sometimes end up listening to a song of theirs I had never heard of before. 

Any help would be greatly appreciated.