I have no idea. I think probably W3 didn't play nice with the newest updates to wordpress and possibly other plugins.
For me it is way too complex of a plugin, and although I've used it very successfully for awhile, I am finished with it. I cannot have plugins that will take down active business websites. Also, the support offered by the W3 team is way too expensive and seems mercenary style based on the knowledge of how complex the plugin and its operations are.
I must say though, that initially the team at W3 did answer all my questions and help me for free with the setup. I wouldn't mind paying either, but not the prices quoted in the admin panel.
Going to give another plugin a shot.