Chloe, Good advice above – especially Daryl’s first bullet. The two most common root causes for this condition are: 1. The Default start time in “Calendar options for this project” is not aligned with the start time of one or more effective calendars, and this has introduced a slight offset when an actual start or finish date has at some point been manually entered. 2. The Default start time, Default end time, and effective calendars have been correctly modified from the out-of-box (Standard) values, BUT the project’s Start date (in the Project Information dialog) has been left unchanged at 08:00 on the first day of the project. If the modified workdays start at 07:00, then this issue creates a 1-hour offset that cascades through the whole schedule from day 1. If no progress has yet been recorded, then fixing the project’s Start date (time) will correct the issue easily.