I came across the exact same problem, it seems to me (from my
experience and from reading the posts in this newsgroup) that for some
reason, DNS in Win2k fails randomly, i.e. it stops performing
recursive queries for no reason at all.
The solution that worked for me was to simply disable forwarders, then
re-enable it and manually re-add the servers you wish to use as
forwarders.
I did that and it works fine: although I have no idea how long it will
last before failing again (if it does that is, as this was the first
time for it to fail)!
I hope this is of some use to those who are as frustrated as I was
trying to reason the cause/solution to this problem.
It would be helpful, though, if someone could provide a reasonable
explanation for this phenomenon??