Logon with Fingerprint reader option disappears without changing a setting

My brand new Latitude D630 (XP pro) is working fine. The only problem(s) I have are related to the fingerprint reader and the Embassy Software.
This software seems to be very unrelyable - under XP and even more problematic under VISTA Business (but VISTA is a different story). I was able set the fingerprint windows XP logon up and in theory it is working. I can login with the registered fingerprints - fine... BUT In practice it often happens that after a screen lock the embassy logonpanel appears but only gives the possibility to logon with a password (not the fingerprint - even it is setup to allow one of the two options). If I reboot the machine then, both options are again available. I have no idea what triggers this behavior because it appears even if did not access the embassy software - not to say that I changed any settings there. From my current view this happens some times completely unexpected.
Is anyone of you seeing the same effect? Did someone get a solution for this?
Many thanks in advance and greetings from Vienna(Europe).
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