The forum program uses the cookie it places on your computer to track whether you have viewed PM's or not. If you access the site from mulitple computers, then there will be two seperate cookies. So, you may read your PM's on one computer, but then when you look at the site from another, it doesn't know you've already read your cookies and shows that you have new PM's.
Also, if you delete your cookie and return to the site, the new cookie doesn't know that you have read your PM's.
All this cookie talk is making hungary.
Brian Latturner
MonsterMuleys.com