Project tasks moving automatically

[tcalderini]

Has anyone experienced the automatic moving of tasks within a plan. I have created a plan and saved it. I then close it or go to a different view. When I return, the order of some tasks has automatically changed. For example, when I saved the plan tasks 10 - 20 were all in numerical order. After going back to the Gantt view, my order can be something like this:

10
11
14
19


12
15
20
16
17
18
13

Any thoughts? Thanks