I set up a default Project Tasks view in Sharepoint 2010. However, the default view, which is supposed to be a Gantt chart, doesn't show up. The other views (e.g. All Tasks, Active Tasks) are working correctly. This is on IE7.
This is likely happening due to a custom master page. See this related post on MSDN. The Gantt view requires the following div to be on the page in order to render the chart:
<div id="s4-workspace">
Check your custom master page to ensure this id has not been removed or changed.