I have the latest version installed ( 88432_wpmu-dev-dashboard-3.2.zip ) and latest WP - it was working fine - then I needed to request that my user account with wpmudev.org be changed - effectively I was given a new one and the full membership transferred over.
Now - whatever I do the dashboard will not come back - I've deleted and reinstalled the plugin, removed all references from wp_options.. cleared and turned off all caching options.
The only clue that it is installed is under dashboard / updates - where I see:
WPMU DEV Plugins/Themes
Your plugins/themes from WPMU DEV are all up to date.
I do not have the same problem on another site which already had WPMU installed.
Are there any extra options, caches of settings I can change to try and get this back up and working - or something else that I'm missing?