I'm not sure of the exact cause of this, but my site at http://www.poppameth.com will display only a white page after the recent update to the latest W3-Total-Cache. There was a wordpress update at about the same time so I'm not sure of where the problem lies. I'm using the Suffusion theme, which also had a recent update. All I can say for sure is that I can see the page fine when logged in, but not when logged out. Deactivating W3TC results in a fully operational page.