回複：有沒有iis 6.0管理高手？俺有一個奇怪的401.2問題難以解決

if you have other PCs are working, then the problem is most likely on the client side.

is the Proxy setting different on the not-working PC?

one thing not very sure is, based on your IIS setting (bot Integrated Authentication and Anonymous), seems like no need for user to enter user name and password...