It appeared from the reports/complaints we received that a number of client systems/resolvers had decided to only request data from the nonfunctional DNS server and despite failing on that wouldn't ask our other listed DNS servers. They therefore could not resolve addresses for otherwise functional network assets. I seem to remember this was somehow related to systems running Microsoft OS's. Am I confused or could it be that Microsoft knows something about this?

MS DNS, WinNT4 and below, have broken search algorithm implementations. DDNS, Win2K, is currently untested.