I was wondering if there was some way to lock a cookie, so that it exists on your PC but the site can no longer edit it. I tried making it read-only, but that didn't do the trick.
I believe quesuerte already tried that and it did not work.
I think the only way to change the way your internet browser handles cookies is to look at privacy settings. In IE, take a look at the Internet Options > Privacy tab and you can stop sites from using cookies but as far as I know, you can not stop a site that already has placed a cookie on your machine from using or manipulating that cookie... unless you want to just block that site from using cookies all together.