Changing % complete changes the start date

[obrian7]

The project file I'm working on has several of the tasks entered as 100% complete, which is incorrect. If I change this to 0%, the start dates are shifted back several months (to 7/5/06). How do reset the percent complete without changing the start/end dates?

 

[PDQBach]

I don't have time to test all the possibilities but start with this scenario.

Setting the task to 0% probably sets the start date back to either the Constraint date or a date that a resource was assigned to the task.

View | Task Usage and insert the Constraint Date column
Window | Split and in the bottom half of the screen, RightMouseButton on a gray area and click on Resource Schedule.

Set a task %Complete back to 0 and I expect you'll see the Start date get set to either the Constraint date or to the earliest date that a resource was assigned to work on the task.

 

[obrian7]

I found the problem. Under the Task Information, the constraint was set to "As Early As Possible". When I changed this to a fixed start date, I could set the percent completion to zero without the dates shifting.