I simplify the script (no kixforms this time) and i have the same error message...
When i put directly "kix32.exe logon.kx" in the "start program on connection" i got a "This initial program cannot be started"

about association, i don't know if it is really the problem because there is no problem if i launch the same script.kx after the user has logged on...
how do you do ? do you always run you kixscript or logonscript from a batch?