Progressin activities with Data Line Issues

Hi,

1. When I use the data line to update my activities, it automatically completes certain tasks which should still be in progress?

2. Once some activities have been progressed, I F9 and some of the increase in duration?

3. If I manually select a task 'Start' or Finish then the successor will fall back to the data line?

I have a really large schedule and these occurrunces are making it hard for me to manage the schedule.

Please any help?

Thanks