Can’t Deactivate Invoices Subscriptions Plugin

I am having trouble deactivating the Sliced Invoices Subscriptions plugin.

On the Plugin screen, when clicking the Deactivate link underneath the Sliced Invoices Subscriptions title, the browser page advances to a ‘This page isn’t working’. Nothing happens when checking the box, and then trying the same through the “bulk edit” drop down; delete doesn’t work either.

Any help would be much appreciated.