A couple of things to check. I am using MSOP 2010 Professional. From this version go into the File tab, selection Options and select the schedule tab. This is where the default start time and default end times are defined. You could also have a calendar set with different start and end times. This is set through the project tab and then the change working time. Please note that if you have a resource assigned that they have a calendar defined for them as well. One last thought is that option in MSOP 2010 that also allows you to assign a calendar to a task. This would show up in the indicator column.
