ipv6 & login frame

[Liviu Pislaru]

hi,

i'm deeply surprised to see that if i'm using IPv6 i cannot login on 
this website (http://www.arbetsformedlingen.se) and i even get an 
explicit message. (see the links below)
https://www.dropbox.com/s/tzuom0p1ka3tpgz/v6_login_english.png
https://www.dropbox.com/s/tbxvkkmjwi8sxq5/v6_login.png

do you know about similar issues with any other website ?
does anyone has an explanation for this ?
security issues, geolocation issues ... what do they want to avoid ?

thanks
--
liviu.