Vista - "Media unauthenticated" when bypassing WLan AutoConfig

Our wireless management utility uses OID_802_11_* codes to manage wireless
adapters under Windows 2000/XP. In both cases this implies stopping the
Wireless Zero Config (wzcsvc) service. This works fine.

I have been experimenting with our MSDN release of Vista (Business Edition
in this case), trying to replicate that same behavior. I am thus stopping
the WLan AutoConfig (wlansvc) service. However, when I associate to a
network using our normal OID sequence (OID_802_11_INFRASTRUCTURE_MODE,
OID_802_11_AUTHENTICATION_MODE, OID_802_11_ADD_WEP, OID_802_11_WEP_STATUS,
OID_802_11_BSSID, OID_802_11_SSID) I do not get the expected result. The
wireless adapter associates fine with the access point, but the actual
network connection does not seem to get enabled (the ipconfig tool shows the
connection as being in the "media unauthenticated" state and thus does not
seem to be assigned its IP information).

This is obviously some new behavior in Windows Vista and I still haven't
found a way around it.

Any ideas?

-Benoît Bousquet