Sounds like the site you are trying to use is being far too aggressive in it's adblock detection.
What site is it?
The sites I am having the issue with are sites I haveused before (rainpool, alekscoin, luckybits). I do not have this issue on facuets I have never visited. MexicanTarget said it was my cookies, but I have re-installed fresh browsers, ran a different browser on a different operating system inside a virtural machine, deleted cookies ect and still getting the error
Try disabling all your plugins in Chrome/Firefox, or whatever browser you're using, then re-enable each of them one-by-one to see if any of them are responsible. Secondly, see if your AV is stopping it. Third, are you surfing behind a proxy or 3rd-party DNS service provider (e.g. OpenDNS)? I've had issues with various combinations in the past, and these are generally the first set of troubleshooting ideas I use.
Nothing had changed on my computer from being able to use to getting the error. I am not suing proxy, not using 3rd party DNS, its not my AV.
The browsers I have tried while still getting the error are clean install, no cookies, no add-ons, no pug-in, completely vanilla.
I have uninstalled and reinstalled new browsers, tried on linux where my AV does work (virtual machine) with vanilla browser (no addons, no anything) and still getting the error only on the faucet sites I have previously used