I have the same problem as this, although my whole site goes down, including the admin. Whilst I have managed to deactivate the plugin is there a fix for this issue?
I am using wordpress 4.2.3
Nextgen Gallery 2.1.2
Seems to happen with all themes but currently running with an unaltered 2014 theme.
I PHP is 5.3 on Apache running as FastCgi
I have just migrated servers, I am fairly sure that this was OK on my old server. Which would suggest a setting somewhere. Any ideas what it could be would be great.