Why when clicking on the name of a map when viewing them (and being able to scroll through them) on the Boards page does a new Tab (in Firefox) open to the link http://www.wargear.net/boards/undefined ?

I don't get that.

What I said or the issue?

I don't get the issue either!?!

Either. I tried opening every link I could find from within the board tab and couldn't replicate what you described.

1. Go to the Boards tab.
2. Click on the Map Image so the Flash Board Preview thingy (that's what I'm calling it, do you know what I'm talking about?) comes up. 
3. In the Map Preview thingy the name of the Map is just below the map image and just above the Close line, click on the name (your mouse changes to as if you can Highlight the map name).
4. New tab opens to the link above, I assume it should take you to the Board Info page (or I think it should anyways since you can flip through the Board images in the Flash Board Preview thingy).

If I could upload an image directly I'd highlight it with a screenshot :P

Another scenario with similar outcome:

1. Go to Join Game when active game is present
2. Click on the map image of the game to load the Flash Board Preview thingy.
3. Click on the name of the map (same as above)
4. New tab opens to the following link http://www.wargear.net/games/list/undefined/1/?viewselector=all&sortfield=games.startstamp&sortorder=desc&showdays=all

I dunno what that's supposed to show or what it's for.

That is weird.