Cookies or other headers disappearing, can cause 'out-of-memory'

We just had a case recently where the customer saw their cookie disappear when they did a large form post.  After looking into it further, we discovered that the problem was KB 819876

Basically we were including the POST data in the size we use to calculate the size of the header data.  So that made it so that the custom filter was unable to add it's own headers and got the problem.  It can also cause cookies to be deleted, which can cause all sorts of unknown problems depending on what the cookie was used for.