Cannot see the WPMU Dev Dashboard

I'm no longer able to see my WPMU Dev Dashboard in Wordpress. I thought it could be a corrupt file so reinstalled using the latest version with FTP but nope, its still invisible.

If I goto the plugin update screen, its telling me there are updates available to other WPMU plugins but I am unable to make the changes within the dashboard. I have to download a fresh copy of each to my machine.

Can you help please.

Thanks

James.