FYI for others who may try this plugin, then remove it, as I did.
I had used this plugin a while back, then decided against it and removed it via the WP plugin page.
Yesterday, I made some changes to my site but no matter what I did, old cached pages were showing up in certain browsers (IE6 and IE7. For whatever reason, Firefox found the new version).
Finally I went in via FTP and looked at my files - sure enough, there was an old w3tc folder under WP-content. After I deleted that folder, my new pages showed up properly in all browsers.
So, if you're having problems - look for that folder.
