LogonStudio Vista requires Windows Vista,
you can not run Windows XP & install & use LogonStudio Vista.
LogonStudio Vista only works with rtm releases of Windows Vista,
you cannot use a CTP release of Vista (community technology preview) like beta 1,2, rc1 or rc2.
LogonStudio Vista will not work on any beta vista release.
Did you upgrade to Vista from Windows XP?
You wouldn't think that would cause a problem but you never know....
Are you using a rtm release or beta version of Vista?
This info would help alot.