Unable to see installed Snapshot plugin options and unable to install or reinstall

Hi there

I have noticed that my Snapshot plugin is no longer appearing in my WP option menu. The folder is on the server, and looking at WPMU Dev it says that it is installed, but I can't see it.

I have tried installing from the Plugin page on the WPMU Dev dashboard but just get an error.

I have also tried renaming the folder on the ftp site and then trying the reinstall it via the panel but get the error.

The site is a multisite on http://www.50ftwoman.com and was working fine up until about 31st May according to the Dropbox backup.

I'm not sure what to try!