I've been having problems with this Archive button as well.  I don't use archiving, but I keep hitting the button by accident since it's next to the reply button.  Since I don't have an archive folder set up, the mail that I accidentally "archived" keeps going to some secret place that I can't find.  As was mentioned below, there doesn't seem to be any settings or functions available to change the archiving.  As a result, I have emails sitting in some "secret" archive folder that I can't access.  Any suggestions on how to find my messages?  

Thanks!