Opera responds to the link "Forums" with:

Could not locate remote server

You tried to access the address http://www.boincstats.com.com/forums/index.php?showforum=, which is currently unavailable. Please make sure that the Web address (URL) is correctly spelled and punctuated, then try reloading the page.

INterestingly enough, firefox works.

The forum is now opened in a new window.

The code to show the forum in the 'main view' part of BOINCstats was always buggy (but tested by me on IE, FF and Opera and found working) so I think this is a better (but not nicer) way the open the forum.

Yes, it is better. Actually I had added www.boincstats.com/forums/index.php to favourites and was using it instead of link from the main page. So, in fact it is also nicer to me

One more suggestion.
Since forum is not localised, let the link lead to www.boincstats.com/forums/index.php instead of xx.boincstats.com/...

As it is now, when you click on a link, you're redirected to (for example): pl.boincstats.com/forums/index.php, where you have to log in to forum. But when you are logged in, you're redirected to www.boincstats.com/forums/index.php , and this is, where your cookie is set.
In other words, you never get a cookie for a localised domain, so you have to log in each time.

Well...actually, you can get a cookie for localised domain, but you have to manually change URL in browser address bar just after logging into forum.