That’s strange – can you confirm if this occurs when you use a default and unmodified theme, such as Twenty Twelve?
If it does still persist then before reactivating your own theme can you try deactivating all other plugins except for those by Modern Tribe and see if it is still an issue?
Hopefully though these steps will resolve the problem – you should then reactivate all other components one-at-a-time, testing at each stage to see if the issue has returned. If and when it does re-occur please take note of whatever component, whether that’s your theme or a plugin, seems to be causing it: we can then focus on trying to find a solution.
Thanks!