I THINK this has to do with whatever they're using to emulate the CD, but I'm not 100% sure.
When I start the game and go from the main screen to any combat instance, the game locks up when I get out. If I catch it by alt-tabbing I see either a disk error or a crashing error of C0x000000 etc.
I am running Vista 64 Home Premium. I have disabled UAC. Going to try a few other things (like running in compatibility mode) but in the meantime if anyone else has any ideas, I am totally game.

Here is an image of the crash error.
I have also tried running in compatibility mode (XP SP2) as well as setting the game to run on one affinity.
[edit] After updating my video card drivers (?!) and rebooting a couple of times it seems to have resolved the issue. <3 this game!

That image says that this is a StackWalk:126 error, which, according to random net people, is a graphical error. What is your video card and driver revision?