There are many issues like yours on the internet – losing Editor after upgrading.
First of all, try disabling all the plugins which are not required by the theme.
If you can, try switching to the default theme just to make sure if it’s theme issue or not (i believe not, because a lot of users is running WP 4.1 with our theme).
Try using another browser and even computer. Empty the browser’s cache.
If nothing of the above solves the problem, could you post your login information so I can check it out?
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