New Posts not resetting

[Jaxx]

For about a week or two, i've now had an issue on my site with the new posts count is not resetting.

When users come to the site, it might have the correct # of posts from their last visit, but as soon as they click on it or read a thread, the new count will raise quite a bit. Its as if the cookies are not being reset.

Any help in what I might look for would be appreciated.