We have multiple color overlay calendars on our site, but for one of our departments the Title link of the events has suddenly stopped working. When anyone clicks on the title of an existing event it either opens a pop-up window with the event title at the top and just a blank box below (even if you go to the individual calendars) or another calendar window with the Page Title link showing info similar to "Page Name": "Calendar Name": "Event Title" and the main area of that window will be blank. I am an administrator for the site and have full permissions, but it is happening for me also.
The other calendars on our site still work fine -- when you click an event title, it opens the edit form for that event. This calendar worked fine when it was set up and this just started two days ago. No one has made any changes to the list settings for the calendar.
Also, if you are in a specific calendar view and click on the event box (anywhere but the title) you can select Edit Item from the Items tab and it will open the edit form normally. If you are not on that specific calendar, the Edit Item button is greyed out.
Any ideas on what could be causing this?