I noticed and error message in W3TC said my wp-contents sub was set wrong at 777. Check and it was 777 so I changed it to 755 as suggested.
W3TC overwrote my htaccess file with stuff that took my site down with a 500 error. The only way to fix it was to restore the htaccess file.
This happens everytime I touch W3TC. The first time last fall I had to get the HostGator to restore the site - they told me how to do it myself - just delete the W3TC code.
Why is that?