Ok, this week i started deploying KIX in vista also.

A few things :

You added that user to the local admins? or added domain users to local admin?

Put your login script in the \\servername\netlogon and let the group policy logon script start from there.

Do you launch your logon script trough a cmd/batch file?

Disabling the UAC on the machine, fixed the problems i had with Vista before, for the moment i got it working with UAC turned on. (only when i trigger wkix32 directly from GPO without a batch file in between, because at that point the file runs as SYSTEM.)

SETTIME for example is one of the things you would need local admin rights for...

Also i noticed, that with the new kixforms dll(now using old version again), my form didn't really show up well, but that could be because of my crappy programming..

I hope this helps a bit, i'll be spending the next days to finalize my logon procedure..

So far for my first post ;\)