When I tried deploying preview settings, WP displayed an error stating "Are you sure you want to do this? Please try again." This was on a site with WP 3.2.1 and W3TC 0.9.2.4. I disabled all plug-ins but the error persisted. I ended up having to disable preview mode and enable the settings "live".
If I had to guess, I would say this problem might be related to WP 3.2.X since all other plugins were disabled and I haven't experienced this problem before using earlier versions of WP. But I can't say for sure.