googlebot, msn and yahoo keept hitting cookie_usage.php and stopping there

[AWWWW.WAHWAH]

I am not sure why this is all of the sudden happening but those three bots are hitting cookie_usage.php which is creating a 302 redirect. None of our coding or configuration has changed. This just started two days ago and all the search engines are deindexing our site.

force cookies is off and always has been, prevent spider sessions is set to true, always has been.

So I'm wondering what could have changed on our end?

 

we went ahead and added cookie_usage.php to our robots.txt file so it will not be indexed but the bots still hit them. Any clues what may have happened in the last two days?