Requires Views and the Date API (packaged with the Date module).
This module will display any Views date field in calendar formats, including CCK date fields, node created or updated dates, etc. Switch between year, month, and day views. Back and next navigation is provided for all views. Lots of the Calendar functionality comes from the Date module, so any time you update the Calendar module you should be sure you also update to the latest version of the Date module at the same time.
See also Date iCal, a project that contains code and features needed to either import or export dates using iCal feeds. The functionality that used to be in the Calendar iCal module has been moved into that module.
Be sure to read Debugging Information before reporting a problem. Going through those steps may resolve your problems and will help provide enough information to tell if this is a bug.