I've just installed DII (+LoD) on a new laptop running Vista 64 bit. The game runs just fine, but when I get to the main menu, everything is greyed out except Single Player. I can't even click Multiplayer or Battle.net. It looks as if it can't find the internet or something. The computer is, in fact, connected to the internet when I play the game. I can't even attempt to connect to anything. The buttons are just greyed out and non-functional.

I have the game installed on another computer (a different CD key) that is running Vista 32 bit and I have no problems. I've done all the obvious things on both systems: set the game to run as administrator, put it in XP SP2 compatibility mode, made sure Windows firewall isn't blocking it, etc. In any case, the settings are identical. On one system it works, and on the other it doesn't.

Can anyone shed some light on the problem? Is there a problem with Vista 64 specifically? There doesn't seem to be any info on the support pages besides the general Vista advice.