Thanks to Drasko Markovic and Paul Czywczynski for pointing out that Microsoft has retracted the LSA post-SP3 hot-fix for Windows NT 4.0 that I mentioned in yesterday's WinInfo. According to a message from Microsoft's Paul Leach, Microsoft has verified that the original hot-fix they posted is indeed a problem. The fix has been withdrawn while Microsoft determines the cause and create a new fix. The problem has the same effect as disabling caching of domain logons, that is, you can't log in if the domain controller can't be contacted. Microsoft expects that the impact will mostly be limited to laptops that frequently operate while disconnected from their domain controller, although other scenarios are certainly possible.
I'll post information about a new version of the fix as soon as it becomes available