I bought PSU awhile back when I still had XP, after upgrading to Vista some time ago I can't get it to run. All I get now is a Japanese Error Message.
Has anyone run into, and fixed this issue?
Apparently, though I don't have the game so I can't confirm, you can do the following things to get it to work:
Alternatively, you could buy and install the expansion pack, "Phantasy Star Universe: Ambition of the Illuminus" - its system requirements include Windows Vista so it should be compatible.
If none of the above works, I would contact Sega and see if they can help you any more.