I answered a post a few days ago where someone was having problems with the cart opening a new window/ tab as opposed to the popup cart. I was following the thought of maybe being related to the users' browsers disabling java.
Now I just made new buttons, and I'll be $#@%% if I'm not having the same problem. I tried the standard button and a button with no java (by unchecking the option above the code). Either way, the button opens a new page.
What gets me is I'm am using templates. The new dysfunctional page is identical to the page that currently works. So of course my bowser, etc. is not the problem.
Edit: lol, to add more confusion. I just put the same new button code on the existing page that has my first batch of buttons on it- and it opens the popup correctly. I put the code on existing pages that did NOT already have buttons and it opens in a new window. What the heck? hehe, this one is going to keep me up all night.