Merry Christmas, Bret!
I know Randy had some issues with Vista and Mac OS back in the day. It sounds like you might be running into some of the same issues.
Out of curiosity, which programming language is the game written in? And have you considered a cross-platform language like Java?
I'm not an expert or trying to tell you what you should do... I'm just curious as I have done a little programming myself, but just as a hobby and nothing as complex as an internet game.
Hope you didn't take that the wrong way. Like I said, I'm just curious and appreciate that you are trying to get it back up and running and am confident you will figure everything out after the new year.
Until then, Happy Holidays!