I believe I have a fix for the disabled buttons in Dungeon Siege 2. Not fully confirmed, but it works both for me via Steam and for a friend via a retail copy.
Open your hostsfile in Notepad. (The hostsfile can be found in C:\Windows\system32\drivers\etc\ , and is named "hosts".)
Paste this line at the end of the file:
Save and exit, then run DS2.