Maximum sorted posts limitation ?

Hi, I noticed that sometimes I have none posts displayed when I have to many posts sorted (roughly > 100). Moreover even if I remove posts in sorted list it does not fix the problem. Each time I have to remove ALL posts from sorted list and then restart to sort from empty list !
Any idea ?
Regards

http://ww.wp.xz.cn/extend/plugins/q2w3-post-order/