Using W3TC on WordPress 3.5, with APC. This wasn't a problem last week. Today, I went to edit my menu and saw this:
Warning: apc_store() expects parameter 3 to be long, string given in /home/user/public_html/wp-content/plugins/w3-total-cache/lib/W3/Cache/Apc.php on line 41
Thus far, I only see it on the Appearance -> Menu screen.