I have the same problem. I cannot change security (always set to Essentially Off), Development Mode (always set to Off) and Rocket Loader (always set to Off). I am currently in discussions with CloudFlare support.
I have one site on another host and I do not see those problems. I can change security and development mode so I am thinking it is my primary host that has the issue.
So far, CloudFlare tech support had me run a line of code on my server that used my e-mail address and API key and send them the output.
The problem appears to have been fixed. There was no one clear culprit. There was some kind of timeout occurring between my websites and CloudFlare and that caused the error messages.
The problem cleared up for me and wavesoftech after CloudFlare fixed an issue with IPv6 connectivity to http://www.cloudflare.com but they were not sure that was the root of the problem.
Nevertheless, I no longer have the error messages and I can change my settings in W3 Total Cache without getting error messages.
Only certain hosts were affected by this so this must have been a bad combination of specific host configurations with CloudFlare.
Please refer this thread hope will help.
