We have an overlay calendar for one of our departments that was working fine for a few months, but now the events can not be edited from the overlay view. In fact, whenever a user clicks on the Title of an event, it either brings up a small window with the event title at the top and a blank white space underneath or it opens a new window where the main place holder area is empty. With the new window the "Browse" tab is the only tab visible -- the "View" and "Custom Commands" tabs are not there.
The calendar worked fine until last week and no one has made any changes to that subsite. We have other overlay calendars for other departments and they are all still working fine.
I have checked all the permissions and they have not changed. The users attempting to edit the events all have at least "Contribute" permissions, and I have Full Control but none of us can edit the events by clicking on the titles.
If we go to a specific calendars view and click on an events box (not the title), then we can click the Edit Item button under Manage (in the Events tab), but the title still does not work.
Any idea of what could be causing this?