Page not found when i click on header and archives

Instead of http://www.thezenapproach.com/archives coming up this comes up in the address bar:

http://www.thezenapproach.com/archives%3C/a%3E%3C/div%3E%20%20%20%20%20%20%20%20%3C/li%3E%3C/ul%3E%3C/div%3E%3C/div%3E%3C/div%3E%3C/div%3E%3C/div%3E%3Cdiv%20id=

It happens when i click on archives and on my header (although it doesn’t happen everytime).

Anyone know what’s going on. Here’s my website

Thanks