How strange. I strongly suspect this is due to a peculiarity of your theme; before we go any further though would it work for you to change the default template setting in Events > Settings > Display?
For instance, if it is currently Default Page Template can you try Default Events Template or vice versa?
If that doesn’t help can you try (temporarily) switching to a default theme like Twenty Twelve just to check if it is indeed your particular theme that’s causing the issue (and if so we can then focus in on why it’s doing that).
Thanks!