Plugins and Themes page's in the DEV dashboard don't gracefully handle the usage of DISALLOW_FILE_MODS.
If DISALLOW_FILE_MODS is set then the text "Nice Try..." is displayed.
This is due to the way capabilities are handled in the core. Check wp-includes/capabilities.php
As I'm new to WPMU DEV I don't know what these screens are supposed to display or if any of it is relevant if those capabilities aren't available.
Regardless it would be nice to catch DISALLOW_FILE_MODS and show more relevant error message.