Corel Draw 8 loses objects from a group when moving it.

I experience Problems with a group of objects in Corel 8. When the group is first defined everything works fine. It can be moved around with ease. Later on after I have worked on other parts of the drawing I go back to the old group and want try to move it but instead of moving the entire group as one would expect some of its objects just stay behind and have to be grouped again. Is there a patch for this problem or am I doing something wrong?