Having a problem as well. Something is leading to a 404 in the stats iframe in the dashboard. My entire domain is controlled by WordPressso this loads the WordPress front end inside of the admin panel’s stats iframe. Due to some frame busting JavaScript in my theme the Dashboard crashes completely — the 404 from the stats window breaks out of the iframe (which it should do given the code in my theme) and tries to load the stats iframe page again which just leads to a nasty redirection loop.
For those affected and unable to access the dashboard, only the front dashboard page is affected from my testing– you can deactivate the stats plugin either by deleting its folder (wp-stats) inside of your plugins folder or visit:
https://your.wordpress.url/wp-admin/plugins.php
and deactivate it as normal.