I'm running RC1 of Vista 64bit and Max 9 64bit and it works. The screen is kinda flaky because of poor Nvidia drivers, but the software runs ok. What type of problem are you having?
Hmm - yeah, the people from Autodesk that I've talked with all say that Max 9 isn't officially supported on Vista yet so I imagine it's probably hit or miss depending on what type of hardware you've got, etc. You can bet, though, that they'll release a patch for it pretty soon after the release of Vista. -Ben