When a task is closed via the "close task" button, it doesn't alter the start/end dates for the task and the effect is immediate.
This means when a timesheet is opened that contains a closed task, an error is displayed to the user saying they can no longer allocate time to this task. This has the effect that the user moves the time away from the task.
This causes problems when the task has an estimated number of hours which has now been reached and you do not want anymore time allocated to it. The user moves the time to another project/task because of the error displayed when timesheet is opened and this has the knock on effect that the task is now under the estimated value. As administrator I have to juggle time around to put the task back to 100%.
It would help when a task is closed that the end date is set to the day the task was closed and that the error would only appear to the user if they try to allocate time past the end date.
Also, there is a problem in setting an end date to a task. If there is no start date specified then the start date is set to the same as the end date. Again if a timesheet is opened an error is displayed to the user even though there maybe no time allocated past the end date but I have assumed the error is displayed because there is time before the start date!!!
When a task has an end date specified, does the task automatically become closed after this date i.e."close task" button is ticked automatically and the task has a strikethrough? I have not seen this but it makes sense for this to be an automatic feature.